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51580e79 | 1 | /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com |
969bf05e | 2 | * Copyright (c) 2016 Facebook |
51580e79 AS |
3 | * |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of version 2 of the GNU General Public | |
6 | * License as published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
11 | * General Public License for more details. | |
12 | */ | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/types.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/bpf.h> | |
58e2af8b | 17 | #include <linux/bpf_verifier.h> |
51580e79 AS |
18 | #include <linux/filter.h> |
19 | #include <net/netlink.h> | |
20 | #include <linux/file.h> | |
21 | #include <linux/vmalloc.h> | |
ebb676da | 22 | #include <linux/stringify.h> |
51580e79 AS |
23 | |
24 | /* bpf_check() is a static code analyzer that walks eBPF program | |
25 | * instruction by instruction and updates register/stack state. | |
26 | * All paths of conditional branches are analyzed until 'bpf_exit' insn. | |
27 | * | |
28 | * The first pass is depth-first-search to check that the program is a DAG. | |
29 | * It rejects the following programs: | |
30 | * - larger than BPF_MAXINSNS insns | |
31 | * - if loop is present (detected via back-edge) | |
32 | * - unreachable insns exist (shouldn't be a forest. program = one function) | |
33 | * - out of bounds or malformed jumps | |
34 | * The second pass is all possible path descent from the 1st insn. | |
35 | * Since it's analyzing all pathes through the program, the length of the | |
eba38a96 | 36 | * analysis is limited to 64k insn, which may be hit even if total number of |
51580e79 AS |
37 | * insn is less then 4K, but there are too many branches that change stack/regs. |
38 | * Number of 'branches to be analyzed' is limited to 1k | |
39 | * | |
40 | * On entry to each instruction, each register has a type, and the instruction | |
41 | * changes the types of the registers depending on instruction semantics. | |
42 | * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is | |
43 | * copied to R1. | |
44 | * | |
45 | * All registers are 64-bit. | |
46 | * R0 - return register | |
47 | * R1-R5 argument passing registers | |
48 | * R6-R9 callee saved registers | |
49 | * R10 - frame pointer read-only | |
50 | * | |
51 | * At the start of BPF program the register R1 contains a pointer to bpf_context | |
52 | * and has type PTR_TO_CTX. | |
53 | * | |
54 | * Verifier tracks arithmetic operations on pointers in case: | |
55 | * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), | |
56 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), | |
57 | * 1st insn copies R10 (which has FRAME_PTR) type into R1 | |
58 | * and 2nd arithmetic instruction is pattern matched to recognize | |
59 | * that it wants to construct a pointer to some element within stack. | |
60 | * So after 2nd insn, the register R1 has type PTR_TO_STACK | |
61 | * (and -20 constant is saved for further stack bounds checking). | |
62 | * Meaning that this reg is a pointer to stack plus known immediate constant. | |
63 | * | |
f1174f77 | 64 | * Most of the time the registers have SCALAR_VALUE type, which |
51580e79 | 65 | * means the register has some value, but it's not a valid pointer. |
f1174f77 | 66 | * (like pointer plus pointer becomes SCALAR_VALUE type) |
51580e79 AS |
67 | * |
68 | * When verifier sees load or store instructions the type of base register | |
f1174f77 | 69 | * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK. These are three pointer |
51580e79 AS |
70 | * types recognized by check_mem_access() function. |
71 | * | |
72 | * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' | |
73 | * and the range of [ptr, ptr + map's value_size) is accessible. | |
74 | * | |
75 | * registers used to pass values to function calls are checked against | |
76 | * function argument constraints. | |
77 | * | |
78 | * ARG_PTR_TO_MAP_KEY is one of such argument constraints. | |
79 | * It means that the register type passed to this function must be | |
80 | * PTR_TO_STACK and it will be used inside the function as | |
81 | * 'pointer to map element key' | |
82 | * | |
83 | * For example the argument constraints for bpf_map_lookup_elem(): | |
84 | * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, | |
85 | * .arg1_type = ARG_CONST_MAP_PTR, | |
86 | * .arg2_type = ARG_PTR_TO_MAP_KEY, | |
87 | * | |
88 | * ret_type says that this function returns 'pointer to map elem value or null' | |
89 | * function expects 1st argument to be a const pointer to 'struct bpf_map' and | |
90 | * 2nd argument should be a pointer to stack, which will be used inside | |
91 | * the helper function as a pointer to map element key. | |
92 | * | |
93 | * On the kernel side the helper function looks like: | |
94 | * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) | |
95 | * { | |
96 | * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; | |
97 | * void *key = (void *) (unsigned long) r2; | |
98 | * void *value; | |
99 | * | |
100 | * here kernel can access 'key' and 'map' pointers safely, knowing that | |
101 | * [key, key + map->key_size) bytes are valid and were initialized on | |
102 | * the stack of eBPF program. | |
103 | * } | |
104 | * | |
105 | * Corresponding eBPF program may look like: | |
106 | * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR | |
107 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK | |
108 | * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP | |
109 | * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), | |
110 | * here verifier looks at prototype of map_lookup_elem() and sees: | |
111 | * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, | |
112 | * Now verifier knows that this map has key of R1->map_ptr->key_size bytes | |
113 | * | |
114 | * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, | |
115 | * Now verifier checks that [R2, R2 + map's key_size) are within stack limits | |
116 | * and were initialized prior to this call. | |
117 | * If it's ok, then verifier allows this BPF_CALL insn and looks at | |
118 | * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets | |
119 | * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function | |
120 | * returns ether pointer to map value or NULL. | |
121 | * | |
122 | * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' | |
123 | * insn, the register holding that pointer in the true branch changes state to | |
124 | * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false | |
125 | * branch. See check_cond_jmp_op(). | |
126 | * | |
127 | * After the call R0 is set to return type of the function and registers R1-R5 | |
128 | * are set to NOT_INIT to indicate that they are no longer readable. | |
129 | */ | |
130 | ||
17a52670 | 131 | /* verifier_state + insn_idx are pushed to stack when branch is encountered */ |
58e2af8b | 132 | struct bpf_verifier_stack_elem { |
17a52670 AS |
133 | /* verifer state is 'st' |
134 | * before processing instruction 'insn_idx' | |
135 | * and after processing instruction 'prev_insn_idx' | |
136 | */ | |
58e2af8b | 137 | struct bpf_verifier_state st; |
17a52670 AS |
138 | int insn_idx; |
139 | int prev_insn_idx; | |
58e2af8b | 140 | struct bpf_verifier_stack_elem *next; |
cbd35700 AS |
141 | }; |
142 | ||
8e17c1b1 | 143 | #define BPF_COMPLEXITY_LIMIT_INSNS 131072 |
07016151 DB |
144 | #define BPF_COMPLEXITY_LIMIT_STACK 1024 |
145 | ||
fad73a1a MKL |
146 | #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA) |
147 | ||
33ff9823 DB |
148 | struct bpf_call_arg_meta { |
149 | struct bpf_map *map_ptr; | |
435faee1 | 150 | bool raw_mode; |
36bbef52 | 151 | bool pkt_access; |
435faee1 DB |
152 | int regno; |
153 | int access_size; | |
33ff9823 DB |
154 | }; |
155 | ||
cbd35700 AS |
156 | /* verbose verifier prints what it's seeing |
157 | * bpf_check() is called under lock, so no race to access these global vars | |
158 | */ | |
159 | static u32 log_level, log_size, log_len; | |
160 | static char *log_buf; | |
161 | ||
162 | static DEFINE_MUTEX(bpf_verifier_lock); | |
163 | ||
164 | /* log_level controls verbosity level of eBPF verifier. | |
165 | * verbose() is used to dump the verification trace to the log, so the user | |
166 | * can figure out what's wrong with the program | |
167 | */ | |
1d056d9c | 168 | static __printf(1, 2) void verbose(const char *fmt, ...) |
cbd35700 AS |
169 | { |
170 | va_list args; | |
171 | ||
172 | if (log_level == 0 || log_len >= log_size - 1) | |
173 | return; | |
174 | ||
175 | va_start(args, fmt); | |
176 | log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args); | |
177 | va_end(args); | |
178 | } | |
179 | ||
de8f3a83 DB |
180 | static bool type_is_pkt_pointer(enum bpf_reg_type type) |
181 | { | |
182 | return type == PTR_TO_PACKET || | |
183 | type == PTR_TO_PACKET_META; | |
184 | } | |
185 | ||
17a52670 AS |
186 | /* string representation of 'enum bpf_reg_type' */ |
187 | static const char * const reg_type_str[] = { | |
188 | [NOT_INIT] = "?", | |
f1174f77 | 189 | [SCALAR_VALUE] = "inv", |
17a52670 AS |
190 | [PTR_TO_CTX] = "ctx", |
191 | [CONST_PTR_TO_MAP] = "map_ptr", | |
192 | [PTR_TO_MAP_VALUE] = "map_value", | |
193 | [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", | |
17a52670 | 194 | [PTR_TO_STACK] = "fp", |
969bf05e | 195 | [PTR_TO_PACKET] = "pkt", |
de8f3a83 | 196 | [PTR_TO_PACKET_META] = "pkt_meta", |
969bf05e | 197 | [PTR_TO_PACKET_END] = "pkt_end", |
17a52670 AS |
198 | }; |
199 | ||
ebb676da TG |
200 | #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x) |
201 | static const char * const func_id_str[] = { | |
202 | __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN) | |
203 | }; | |
204 | #undef __BPF_FUNC_STR_FN | |
205 | ||
206 | static const char *func_id_name(int id) | |
207 | { | |
208 | BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID); | |
209 | ||
210 | if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id]) | |
211 | return func_id_str[id]; | |
212 | else | |
213 | return "unknown"; | |
214 | } | |
215 | ||
58e2af8b | 216 | static void print_verifier_state(struct bpf_verifier_state *state) |
17a52670 | 217 | { |
58e2af8b | 218 | struct bpf_reg_state *reg; |
17a52670 AS |
219 | enum bpf_reg_type t; |
220 | int i; | |
221 | ||
222 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
223 | reg = &state->regs[i]; |
224 | t = reg->type; | |
17a52670 AS |
225 | if (t == NOT_INIT) |
226 | continue; | |
227 | verbose(" R%d=%s", i, reg_type_str[t]); | |
f1174f77 EC |
228 | if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && |
229 | tnum_is_const(reg->var_off)) { | |
230 | /* reg->off should be 0 for SCALAR_VALUE */ | |
231 | verbose("%lld", reg->var_off.value + reg->off); | |
232 | } else { | |
233 | verbose("(id=%d", reg->id); | |
234 | if (t != SCALAR_VALUE) | |
235 | verbose(",off=%d", reg->off); | |
de8f3a83 | 236 | if (type_is_pkt_pointer(t)) |
f1174f77 EC |
237 | verbose(",r=%d", reg->range); |
238 | else if (t == CONST_PTR_TO_MAP || | |
239 | t == PTR_TO_MAP_VALUE || | |
240 | t == PTR_TO_MAP_VALUE_OR_NULL) | |
241 | verbose(",ks=%d,vs=%d", | |
242 | reg->map_ptr->key_size, | |
243 | reg->map_ptr->value_size); | |
7d1238f2 EC |
244 | if (tnum_is_const(reg->var_off)) { |
245 | /* Typically an immediate SCALAR_VALUE, but | |
246 | * could be a pointer whose offset is too big | |
247 | * for reg->off | |
248 | */ | |
249 | verbose(",imm=%llx", reg->var_off.value); | |
250 | } else { | |
251 | if (reg->smin_value != reg->umin_value && | |
252 | reg->smin_value != S64_MIN) | |
253 | verbose(",smin_value=%lld", | |
254 | (long long)reg->smin_value); | |
255 | if (reg->smax_value != reg->umax_value && | |
256 | reg->smax_value != S64_MAX) | |
257 | verbose(",smax_value=%lld", | |
258 | (long long)reg->smax_value); | |
259 | if (reg->umin_value != 0) | |
260 | verbose(",umin_value=%llu", | |
261 | (unsigned long long)reg->umin_value); | |
262 | if (reg->umax_value != U64_MAX) | |
263 | verbose(",umax_value=%llu", | |
264 | (unsigned long long)reg->umax_value); | |
265 | if (!tnum_is_unknown(reg->var_off)) { | |
266 | char tn_buf[48]; | |
f1174f77 | 267 | |
7d1238f2 EC |
268 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); |
269 | verbose(",var_off=%s", tn_buf); | |
270 | } | |
f1174f77 EC |
271 | } |
272 | verbose(")"); | |
273 | } | |
17a52670 | 274 | } |
9c399760 | 275 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { |
1a0dc1ac | 276 | if (state->stack_slot_type[i] == STACK_SPILL) |
17a52670 | 277 | verbose(" fp%d=%s", -MAX_BPF_STACK + i, |
1a0dc1ac | 278 | reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]); |
17a52670 AS |
279 | } |
280 | verbose("\n"); | |
281 | } | |
282 | ||
cbd35700 AS |
283 | static const char *const bpf_class_string[] = { |
284 | [BPF_LD] = "ld", | |
285 | [BPF_LDX] = "ldx", | |
286 | [BPF_ST] = "st", | |
287 | [BPF_STX] = "stx", | |
288 | [BPF_ALU] = "alu", | |
289 | [BPF_JMP] = "jmp", | |
290 | [BPF_RET] = "BUG", | |
291 | [BPF_ALU64] = "alu64", | |
292 | }; | |
293 | ||
687f0715 | 294 | static const char *const bpf_alu_string[16] = { |
cbd35700 AS |
295 | [BPF_ADD >> 4] = "+=", |
296 | [BPF_SUB >> 4] = "-=", | |
297 | [BPF_MUL >> 4] = "*=", | |
298 | [BPF_DIV >> 4] = "/=", | |
299 | [BPF_OR >> 4] = "|=", | |
300 | [BPF_AND >> 4] = "&=", | |
301 | [BPF_LSH >> 4] = "<<=", | |
302 | [BPF_RSH >> 4] = ">>=", | |
303 | [BPF_NEG >> 4] = "neg", | |
304 | [BPF_MOD >> 4] = "%=", | |
305 | [BPF_XOR >> 4] = "^=", | |
306 | [BPF_MOV >> 4] = "=", | |
307 | [BPF_ARSH >> 4] = "s>>=", | |
308 | [BPF_END >> 4] = "endian", | |
309 | }; | |
310 | ||
311 | static const char *const bpf_ldst_string[] = { | |
312 | [BPF_W >> 3] = "u32", | |
313 | [BPF_H >> 3] = "u16", | |
314 | [BPF_B >> 3] = "u8", | |
315 | [BPF_DW >> 3] = "u64", | |
316 | }; | |
317 | ||
687f0715 | 318 | static const char *const bpf_jmp_string[16] = { |
cbd35700 AS |
319 | [BPF_JA >> 4] = "jmp", |
320 | [BPF_JEQ >> 4] = "==", | |
321 | [BPF_JGT >> 4] = ">", | |
b4e432f1 | 322 | [BPF_JLT >> 4] = "<", |
cbd35700 | 323 | [BPF_JGE >> 4] = ">=", |
b4e432f1 | 324 | [BPF_JLE >> 4] = "<=", |
cbd35700 AS |
325 | [BPF_JSET >> 4] = "&", |
326 | [BPF_JNE >> 4] = "!=", | |
327 | [BPF_JSGT >> 4] = "s>", | |
b4e432f1 | 328 | [BPF_JSLT >> 4] = "s<", |
cbd35700 | 329 | [BPF_JSGE >> 4] = "s>=", |
b4e432f1 | 330 | [BPF_JSLE >> 4] = "s<=", |
cbd35700 AS |
331 | [BPF_CALL >> 4] = "call", |
332 | [BPF_EXIT >> 4] = "exit", | |
333 | }; | |
334 | ||
2b7c6ba9 EC |
335 | static void print_bpf_end_insn(const struct bpf_verifier_env *env, |
336 | const struct bpf_insn *insn) | |
337 | { | |
338 | verbose("(%02x) r%d = %s%d r%d\n", insn->code, insn->dst_reg, | |
339 | BPF_SRC(insn->code) == BPF_TO_BE ? "be" : "le", | |
340 | insn->imm, insn->dst_reg); | |
341 | } | |
342 | ||
0d0e5769 DB |
343 | static void print_bpf_insn(const struct bpf_verifier_env *env, |
344 | const struct bpf_insn *insn) | |
cbd35700 AS |
345 | { |
346 | u8 class = BPF_CLASS(insn->code); | |
347 | ||
348 | if (class == BPF_ALU || class == BPF_ALU64) { | |
2b7c6ba9 EC |
349 | if (BPF_OP(insn->code) == BPF_END) { |
350 | if (class == BPF_ALU64) | |
351 | verbose("BUG_alu64_%02x\n", insn->code); | |
352 | else | |
353 | print_bpf_end_insn(env, insn); | |
73c864b3 EC |
354 | } else if (BPF_OP(insn->code) == BPF_NEG) { |
355 | verbose("(%02x) r%d = %s-r%d\n", | |
356 | insn->code, insn->dst_reg, | |
357 | class == BPF_ALU ? "(u32) " : "", | |
358 | insn->dst_reg); | |
2b7c6ba9 | 359 | } else if (BPF_SRC(insn->code) == BPF_X) { |
cbd35700 AS |
360 | verbose("(%02x) %sr%d %s %sr%d\n", |
361 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
362 | insn->dst_reg, | |
363 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
364 | class == BPF_ALU ? "(u32) " : "", | |
365 | insn->src_reg); | |
2b7c6ba9 | 366 | } else { |
cbd35700 AS |
367 | verbose("(%02x) %sr%d %s %s%d\n", |
368 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
369 | insn->dst_reg, | |
370 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
371 | class == BPF_ALU ? "(u32) " : "", | |
372 | insn->imm); | |
2b7c6ba9 | 373 | } |
cbd35700 AS |
374 | } else if (class == BPF_STX) { |
375 | if (BPF_MODE(insn->code) == BPF_MEM) | |
376 | verbose("(%02x) *(%s *)(r%d %+d) = r%d\n", | |
377 | insn->code, | |
378 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
379 | insn->dst_reg, | |
380 | insn->off, insn->src_reg); | |
381 | else if (BPF_MODE(insn->code) == BPF_XADD) | |
382 | verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n", | |
383 | insn->code, | |
384 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
385 | insn->dst_reg, insn->off, | |
386 | insn->src_reg); | |
387 | else | |
388 | verbose("BUG_%02x\n", insn->code); | |
389 | } else if (class == BPF_ST) { | |
390 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
391 | verbose("BUG_st_%02x\n", insn->code); | |
392 | return; | |
393 | } | |
394 | verbose("(%02x) *(%s *)(r%d %+d) = %d\n", | |
395 | insn->code, | |
396 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
397 | insn->dst_reg, | |
398 | insn->off, insn->imm); | |
399 | } else if (class == BPF_LDX) { | |
400 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
401 | verbose("BUG_ldx_%02x\n", insn->code); | |
402 | return; | |
403 | } | |
404 | verbose("(%02x) r%d = *(%s *)(r%d %+d)\n", | |
405 | insn->code, insn->dst_reg, | |
406 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
407 | insn->src_reg, insn->off); | |
408 | } else if (class == BPF_LD) { | |
409 | if (BPF_MODE(insn->code) == BPF_ABS) { | |
410 | verbose("(%02x) r0 = *(%s *)skb[%d]\n", | |
411 | insn->code, | |
412 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
413 | insn->imm); | |
414 | } else if (BPF_MODE(insn->code) == BPF_IND) { | |
415 | verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n", | |
416 | insn->code, | |
417 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
418 | insn->src_reg, insn->imm); | |
0d0e5769 DB |
419 | } else if (BPF_MODE(insn->code) == BPF_IMM && |
420 | BPF_SIZE(insn->code) == BPF_DW) { | |
421 | /* At this point, we already made sure that the second | |
422 | * part of the ldimm64 insn is accessible. | |
423 | */ | |
424 | u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; | |
425 | bool map_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD; | |
426 | ||
427 | if (map_ptr && !env->allow_ptr_leaks) | |
428 | imm = 0; | |
429 | ||
430 | verbose("(%02x) r%d = 0x%llx\n", insn->code, | |
431 | insn->dst_reg, (unsigned long long)imm); | |
cbd35700 AS |
432 | } else { |
433 | verbose("BUG_ld_%02x\n", insn->code); | |
434 | return; | |
435 | } | |
436 | } else if (class == BPF_JMP) { | |
437 | u8 opcode = BPF_OP(insn->code); | |
438 | ||
439 | if (opcode == BPF_CALL) { | |
ebb676da TG |
440 | verbose("(%02x) call %s#%d\n", insn->code, |
441 | func_id_name(insn->imm), insn->imm); | |
cbd35700 AS |
442 | } else if (insn->code == (BPF_JMP | BPF_JA)) { |
443 | verbose("(%02x) goto pc%+d\n", | |
444 | insn->code, insn->off); | |
445 | } else if (insn->code == (BPF_JMP | BPF_EXIT)) { | |
446 | verbose("(%02x) exit\n", insn->code); | |
447 | } else if (BPF_SRC(insn->code) == BPF_X) { | |
448 | verbose("(%02x) if r%d %s r%d goto pc%+d\n", | |
449 | insn->code, insn->dst_reg, | |
450 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
451 | insn->src_reg, insn->off); | |
452 | } else { | |
453 | verbose("(%02x) if r%d %s 0x%x goto pc%+d\n", | |
454 | insn->code, insn->dst_reg, | |
455 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
456 | insn->imm, insn->off); | |
457 | } | |
458 | } else { | |
459 | verbose("(%02x) %s\n", insn->code, bpf_class_string[class]); | |
460 | } | |
461 | } | |
462 | ||
58e2af8b | 463 | static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx) |
17a52670 | 464 | { |
58e2af8b | 465 | struct bpf_verifier_stack_elem *elem; |
17a52670 AS |
466 | int insn_idx; |
467 | ||
468 | if (env->head == NULL) | |
469 | return -1; | |
470 | ||
471 | memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); | |
472 | insn_idx = env->head->insn_idx; | |
473 | if (prev_insn_idx) | |
474 | *prev_insn_idx = env->head->prev_insn_idx; | |
475 | elem = env->head->next; | |
476 | kfree(env->head); | |
477 | env->head = elem; | |
478 | env->stack_size--; | |
479 | return insn_idx; | |
480 | } | |
481 | ||
58e2af8b JK |
482 | static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, |
483 | int insn_idx, int prev_insn_idx) | |
17a52670 | 484 | { |
58e2af8b | 485 | struct bpf_verifier_stack_elem *elem; |
17a52670 | 486 | |
58e2af8b | 487 | elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); |
17a52670 AS |
488 | if (!elem) |
489 | goto err; | |
490 | ||
491 | memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); | |
492 | elem->insn_idx = insn_idx; | |
493 | elem->prev_insn_idx = prev_insn_idx; | |
494 | elem->next = env->head; | |
495 | env->head = elem; | |
496 | env->stack_size++; | |
07016151 | 497 | if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { |
17a52670 AS |
498 | verbose("BPF program is too complex\n"); |
499 | goto err; | |
500 | } | |
501 | return &elem->st; | |
502 | err: | |
503 | /* pop all elements and return */ | |
504 | while (pop_stack(env, NULL) >= 0); | |
505 | return NULL; | |
506 | } | |
507 | ||
508 | #define CALLER_SAVED_REGS 6 | |
509 | static const int caller_saved[CALLER_SAVED_REGS] = { | |
510 | BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 | |
511 | }; | |
512 | ||
f1174f77 EC |
513 | static void __mark_reg_not_init(struct bpf_reg_state *reg); |
514 | ||
b03c9f9f EC |
515 | /* Mark the unknown part of a register (variable offset or scalar value) as |
516 | * known to have the value @imm. | |
517 | */ | |
518 | static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm) | |
519 | { | |
520 | reg->id = 0; | |
521 | reg->var_off = tnum_const(imm); | |
522 | reg->smin_value = (s64)imm; | |
523 | reg->smax_value = (s64)imm; | |
524 | reg->umin_value = imm; | |
525 | reg->umax_value = imm; | |
526 | } | |
527 | ||
f1174f77 EC |
528 | /* Mark the 'variable offset' part of a register as zero. This should be |
529 | * used only on registers holding a pointer type. | |
530 | */ | |
531 | static void __mark_reg_known_zero(struct bpf_reg_state *reg) | |
a9789ef9 | 532 | { |
b03c9f9f | 533 | __mark_reg_known(reg, 0); |
f1174f77 | 534 | } |
a9789ef9 | 535 | |
f1174f77 EC |
536 | static void mark_reg_known_zero(struct bpf_reg_state *regs, u32 regno) |
537 | { | |
538 | if (WARN_ON(regno >= MAX_BPF_REG)) { | |
539 | verbose("mark_reg_known_zero(regs, %u)\n", regno); | |
540 | /* Something bad happened, let's kill all regs */ | |
541 | for (regno = 0; regno < MAX_BPF_REG; regno++) | |
542 | __mark_reg_not_init(regs + regno); | |
543 | return; | |
544 | } | |
545 | __mark_reg_known_zero(regs + regno); | |
546 | } | |
547 | ||
de8f3a83 DB |
548 | static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg) |
549 | { | |
550 | return type_is_pkt_pointer(reg->type); | |
551 | } | |
552 | ||
553 | static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg) | |
554 | { | |
555 | return reg_is_pkt_pointer(reg) || | |
556 | reg->type == PTR_TO_PACKET_END; | |
557 | } | |
558 | ||
559 | /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */ | |
560 | static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg, | |
561 | enum bpf_reg_type which) | |
562 | { | |
563 | /* The register can already have a range from prior markings. | |
564 | * This is fine as long as it hasn't been advanced from its | |
565 | * origin. | |
566 | */ | |
567 | return reg->type == which && | |
568 | reg->id == 0 && | |
569 | reg->off == 0 && | |
570 | tnum_equals_const(reg->var_off, 0); | |
571 | } | |
572 | ||
b03c9f9f EC |
573 | /* Attempts to improve min/max values based on var_off information */ |
574 | static void __update_reg_bounds(struct bpf_reg_state *reg) | |
575 | { | |
576 | /* min signed is max(sign bit) | min(other bits) */ | |
577 | reg->smin_value = max_t(s64, reg->smin_value, | |
578 | reg->var_off.value | (reg->var_off.mask & S64_MIN)); | |
579 | /* max signed is min(sign bit) | max(other bits) */ | |
580 | reg->smax_value = min_t(s64, reg->smax_value, | |
581 | reg->var_off.value | (reg->var_off.mask & S64_MAX)); | |
582 | reg->umin_value = max(reg->umin_value, reg->var_off.value); | |
583 | reg->umax_value = min(reg->umax_value, | |
584 | reg->var_off.value | reg->var_off.mask); | |
585 | } | |
586 | ||
587 | /* Uses signed min/max values to inform unsigned, and vice-versa */ | |
588 | static void __reg_deduce_bounds(struct bpf_reg_state *reg) | |
589 | { | |
590 | /* Learn sign from signed bounds. | |
591 | * If we cannot cross the sign boundary, then signed and unsigned bounds | |
592 | * are the same, so combine. This works even in the negative case, e.g. | |
593 | * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. | |
594 | */ | |
595 | if (reg->smin_value >= 0 || reg->smax_value < 0) { | |
596 | reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, | |
597 | reg->umin_value); | |
598 | reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, | |
599 | reg->umax_value); | |
600 | return; | |
601 | } | |
602 | /* Learn sign from unsigned bounds. Signed bounds cross the sign | |
603 | * boundary, so we must be careful. | |
604 | */ | |
605 | if ((s64)reg->umax_value >= 0) { | |
606 | /* Positive. We can't learn anything from the smin, but smax | |
607 | * is positive, hence safe. | |
608 | */ | |
609 | reg->smin_value = reg->umin_value; | |
610 | reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, | |
611 | reg->umax_value); | |
612 | } else if ((s64)reg->umin_value < 0) { | |
613 | /* Negative. We can't learn anything from the smax, but smin | |
614 | * is negative, hence safe. | |
615 | */ | |
616 | reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, | |
617 | reg->umin_value); | |
618 | reg->smax_value = reg->umax_value; | |
619 | } | |
620 | } | |
621 | ||
622 | /* Attempts to improve var_off based on unsigned min/max information */ | |
623 | static void __reg_bound_offset(struct bpf_reg_state *reg) | |
624 | { | |
625 | reg->var_off = tnum_intersect(reg->var_off, | |
626 | tnum_range(reg->umin_value, | |
627 | reg->umax_value)); | |
628 | } | |
629 | ||
630 | /* Reset the min/max bounds of a register */ | |
631 | static void __mark_reg_unbounded(struct bpf_reg_state *reg) | |
632 | { | |
633 | reg->smin_value = S64_MIN; | |
634 | reg->smax_value = S64_MAX; | |
635 | reg->umin_value = 0; | |
636 | reg->umax_value = U64_MAX; | |
637 | } | |
638 | ||
f1174f77 EC |
639 | /* Mark a register as having a completely unknown (scalar) value. */ |
640 | static void __mark_reg_unknown(struct bpf_reg_state *reg) | |
641 | { | |
642 | reg->type = SCALAR_VALUE; | |
643 | reg->id = 0; | |
644 | reg->off = 0; | |
645 | reg->var_off = tnum_unknown; | |
b03c9f9f | 646 | __mark_reg_unbounded(reg); |
f1174f77 EC |
647 | } |
648 | ||
649 | static void mark_reg_unknown(struct bpf_reg_state *regs, u32 regno) | |
650 | { | |
651 | if (WARN_ON(regno >= MAX_BPF_REG)) { | |
652 | verbose("mark_reg_unknown(regs, %u)\n", regno); | |
653 | /* Something bad happened, let's kill all regs */ | |
654 | for (regno = 0; regno < MAX_BPF_REG; regno++) | |
655 | __mark_reg_not_init(regs + regno); | |
656 | return; | |
657 | } | |
658 | __mark_reg_unknown(regs + regno); | |
659 | } | |
660 | ||
661 | static void __mark_reg_not_init(struct bpf_reg_state *reg) | |
662 | { | |
663 | __mark_reg_unknown(reg); | |
664 | reg->type = NOT_INIT; | |
665 | } | |
666 | ||
667 | static void mark_reg_not_init(struct bpf_reg_state *regs, u32 regno) | |
668 | { | |
669 | if (WARN_ON(regno >= MAX_BPF_REG)) { | |
670 | verbose("mark_reg_not_init(regs, %u)\n", regno); | |
671 | /* Something bad happened, let's kill all regs */ | |
672 | for (regno = 0; regno < MAX_BPF_REG; regno++) | |
673 | __mark_reg_not_init(regs + regno); | |
674 | return; | |
675 | } | |
676 | __mark_reg_not_init(regs + regno); | |
a9789ef9 DB |
677 | } |
678 | ||
58e2af8b | 679 | static void init_reg_state(struct bpf_reg_state *regs) |
17a52670 AS |
680 | { |
681 | int i; | |
682 | ||
dc503a8a | 683 | for (i = 0; i < MAX_BPF_REG; i++) { |
a9789ef9 | 684 | mark_reg_not_init(regs, i); |
dc503a8a EC |
685 | regs[i].live = REG_LIVE_NONE; |
686 | } | |
17a52670 AS |
687 | |
688 | /* frame pointer */ | |
f1174f77 EC |
689 | regs[BPF_REG_FP].type = PTR_TO_STACK; |
690 | mark_reg_known_zero(regs, BPF_REG_FP); | |
17a52670 AS |
691 | |
692 | /* 1st arg to a function */ | |
693 | regs[BPF_REG_1].type = PTR_TO_CTX; | |
f1174f77 | 694 | mark_reg_known_zero(regs, BPF_REG_1); |
6760bf2d DB |
695 | } |
696 | ||
17a52670 AS |
697 | enum reg_arg_type { |
698 | SRC_OP, /* register is used as source operand */ | |
699 | DST_OP, /* register is used as destination operand */ | |
700 | DST_OP_NO_MARK /* same as above, check only, don't mark */ | |
701 | }; | |
702 | ||
dc503a8a EC |
703 | static void mark_reg_read(const struct bpf_verifier_state *state, u32 regno) |
704 | { | |
705 | struct bpf_verifier_state *parent = state->parent; | |
706 | ||
8fe2d6cc AS |
707 | if (regno == BPF_REG_FP) |
708 | /* We don't need to worry about FP liveness because it's read-only */ | |
709 | return; | |
710 | ||
dc503a8a EC |
711 | while (parent) { |
712 | /* if read wasn't screened by an earlier write ... */ | |
713 | if (state->regs[regno].live & REG_LIVE_WRITTEN) | |
714 | break; | |
715 | /* ... then we depend on parent's value */ | |
716 | parent->regs[regno].live |= REG_LIVE_READ; | |
717 | state = parent; | |
718 | parent = state->parent; | |
719 | } | |
720 | } | |
721 | ||
722 | static int check_reg_arg(struct bpf_verifier_env *env, u32 regno, | |
17a52670 AS |
723 | enum reg_arg_type t) |
724 | { | |
dc503a8a EC |
725 | struct bpf_reg_state *regs = env->cur_state.regs; |
726 | ||
17a52670 AS |
727 | if (regno >= MAX_BPF_REG) { |
728 | verbose("R%d is invalid\n", regno); | |
729 | return -EINVAL; | |
730 | } | |
731 | ||
732 | if (t == SRC_OP) { | |
733 | /* check whether register used as source operand can be read */ | |
734 | if (regs[regno].type == NOT_INIT) { | |
735 | verbose("R%d !read_ok\n", regno); | |
736 | return -EACCES; | |
737 | } | |
dc503a8a | 738 | mark_reg_read(&env->cur_state, regno); |
17a52670 AS |
739 | } else { |
740 | /* check whether register used as dest operand can be written to */ | |
741 | if (regno == BPF_REG_FP) { | |
742 | verbose("frame pointer is read only\n"); | |
743 | return -EACCES; | |
744 | } | |
dc503a8a | 745 | regs[regno].live |= REG_LIVE_WRITTEN; |
17a52670 | 746 | if (t == DST_OP) |
f1174f77 | 747 | mark_reg_unknown(regs, regno); |
17a52670 AS |
748 | } |
749 | return 0; | |
750 | } | |
751 | ||
1be7f75d AS |
752 | static bool is_spillable_regtype(enum bpf_reg_type type) |
753 | { | |
754 | switch (type) { | |
755 | case PTR_TO_MAP_VALUE: | |
756 | case PTR_TO_MAP_VALUE_OR_NULL: | |
757 | case PTR_TO_STACK: | |
758 | case PTR_TO_CTX: | |
969bf05e | 759 | case PTR_TO_PACKET: |
de8f3a83 | 760 | case PTR_TO_PACKET_META: |
969bf05e | 761 | case PTR_TO_PACKET_END: |
1be7f75d AS |
762 | case CONST_PTR_TO_MAP: |
763 | return true; | |
764 | default: | |
765 | return false; | |
766 | } | |
767 | } | |
768 | ||
17a52670 AS |
769 | /* check_stack_read/write functions track spill/fill of registers, |
770 | * stack boundary and alignment are checked in check_mem_access() | |
771 | */ | |
58e2af8b JK |
772 | static int check_stack_write(struct bpf_verifier_state *state, int off, |
773 | int size, int value_regno) | |
17a52670 | 774 | { |
dc503a8a | 775 | int i, spi = (MAX_BPF_STACK + off) / BPF_REG_SIZE; |
9c399760 AS |
776 | /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, |
777 | * so it's aligned access and [off, off + size) are within stack limits | |
778 | */ | |
17a52670 AS |
779 | |
780 | if (value_regno >= 0 && | |
1be7f75d | 781 | is_spillable_regtype(state->regs[value_regno].type)) { |
17a52670 AS |
782 | |
783 | /* register containing pointer is being spilled into stack */ | |
9c399760 | 784 | if (size != BPF_REG_SIZE) { |
17a52670 AS |
785 | verbose("invalid size of register spill\n"); |
786 | return -EACCES; | |
787 | } | |
788 | ||
17a52670 | 789 | /* save register state */ |
dc503a8a EC |
790 | state->spilled_regs[spi] = state->regs[value_regno]; |
791 | state->spilled_regs[spi].live |= REG_LIVE_WRITTEN; | |
17a52670 | 792 | |
9c399760 AS |
793 | for (i = 0; i < BPF_REG_SIZE; i++) |
794 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; | |
795 | } else { | |
17a52670 | 796 | /* regular write of data into stack */ |
dc503a8a | 797 | state->spilled_regs[spi] = (struct bpf_reg_state) {}; |
9c399760 AS |
798 | |
799 | for (i = 0; i < size; i++) | |
800 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; | |
17a52670 AS |
801 | } |
802 | return 0; | |
803 | } | |
804 | ||
dc503a8a EC |
805 | static void mark_stack_slot_read(const struct bpf_verifier_state *state, int slot) |
806 | { | |
807 | struct bpf_verifier_state *parent = state->parent; | |
808 | ||
809 | while (parent) { | |
810 | /* if read wasn't screened by an earlier write ... */ | |
811 | if (state->spilled_regs[slot].live & REG_LIVE_WRITTEN) | |
812 | break; | |
813 | /* ... then we depend on parent's value */ | |
814 | parent->spilled_regs[slot].live |= REG_LIVE_READ; | |
815 | state = parent; | |
816 | parent = state->parent; | |
817 | } | |
818 | } | |
819 | ||
58e2af8b | 820 | static int check_stack_read(struct bpf_verifier_state *state, int off, int size, |
17a52670 AS |
821 | int value_regno) |
822 | { | |
9c399760 | 823 | u8 *slot_type; |
dc503a8a | 824 | int i, spi; |
17a52670 | 825 | |
9c399760 | 826 | slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; |
17a52670 | 827 | |
9c399760 AS |
828 | if (slot_type[0] == STACK_SPILL) { |
829 | if (size != BPF_REG_SIZE) { | |
17a52670 AS |
830 | verbose("invalid size of register spill\n"); |
831 | return -EACCES; | |
832 | } | |
9c399760 AS |
833 | for (i = 1; i < BPF_REG_SIZE; i++) { |
834 | if (slot_type[i] != STACK_SPILL) { | |
17a52670 AS |
835 | verbose("corrupted spill memory\n"); |
836 | return -EACCES; | |
837 | } | |
838 | } | |
839 | ||
dc503a8a EC |
840 | spi = (MAX_BPF_STACK + off) / BPF_REG_SIZE; |
841 | ||
842 | if (value_regno >= 0) { | |
17a52670 | 843 | /* restore register state from stack */ |
dc503a8a EC |
844 | state->regs[value_regno] = state->spilled_regs[spi]; |
845 | mark_stack_slot_read(state, spi); | |
846 | } | |
17a52670 AS |
847 | return 0; |
848 | } else { | |
849 | for (i = 0; i < size; i++) { | |
9c399760 | 850 | if (slot_type[i] != STACK_MISC) { |
17a52670 AS |
851 | verbose("invalid read from stack off %d+%d size %d\n", |
852 | off, i, size); | |
853 | return -EACCES; | |
854 | } | |
855 | } | |
856 | if (value_regno >= 0) | |
857 | /* have read misc data from the stack */ | |
f1174f77 | 858 | mark_reg_unknown(state->regs, value_regno); |
17a52670 AS |
859 | return 0; |
860 | } | |
861 | } | |
862 | ||
863 | /* check read/write into map element returned by bpf_map_lookup_elem() */ | |
f1174f77 | 864 | static int __check_map_access(struct bpf_verifier_env *env, u32 regno, int off, |
17a52670 AS |
865 | int size) |
866 | { | |
867 | struct bpf_map *map = env->cur_state.regs[regno].map_ptr; | |
868 | ||
5722569b | 869 | if (off < 0 || size <= 0 || off + size > map->value_size) { |
17a52670 AS |
870 | verbose("invalid access to map value, value_size=%d off=%d size=%d\n", |
871 | map->value_size, off, size); | |
872 | return -EACCES; | |
873 | } | |
874 | return 0; | |
875 | } | |
876 | ||
f1174f77 EC |
877 | /* check read/write into a map element with possible variable offset */ |
878 | static int check_map_access(struct bpf_verifier_env *env, u32 regno, | |
dbcfe5f7 GB |
879 | int off, int size) |
880 | { | |
881 | struct bpf_verifier_state *state = &env->cur_state; | |
882 | struct bpf_reg_state *reg = &state->regs[regno]; | |
883 | int err; | |
884 | ||
f1174f77 EC |
885 | /* We may have adjusted the register to this map value, so we |
886 | * need to try adding each of min_value and max_value to off | |
887 | * to make sure our theoretical access will be safe. | |
dbcfe5f7 GB |
888 | */ |
889 | if (log_level) | |
890 | print_verifier_state(state); | |
dbcfe5f7 GB |
891 | /* The minimum value is only important with signed |
892 | * comparisons where we can't assume the floor of a | |
893 | * value is 0. If we are using signed variables for our | |
894 | * index'es we need to make sure that whatever we use | |
895 | * will have a set floor within our range. | |
896 | */ | |
b03c9f9f | 897 | if (reg->smin_value < 0) { |
dbcfe5f7 GB |
898 | verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", |
899 | regno); | |
900 | return -EACCES; | |
901 | } | |
b03c9f9f | 902 | err = __check_map_access(env, regno, reg->smin_value + off, size); |
dbcfe5f7 | 903 | if (err) { |
f1174f77 | 904 | verbose("R%d min value is outside of the array range\n", regno); |
dbcfe5f7 GB |
905 | return err; |
906 | } | |
907 | ||
b03c9f9f EC |
908 | /* If we haven't set a max value then we need to bail since we can't be |
909 | * sure we won't do bad things. | |
910 | * If reg->umax_value + off could overflow, treat that as unbounded too. | |
dbcfe5f7 | 911 | */ |
b03c9f9f | 912 | if (reg->umax_value >= BPF_MAX_VAR_OFF) { |
dbcfe5f7 GB |
913 | verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n", |
914 | regno); | |
915 | return -EACCES; | |
916 | } | |
b03c9f9f | 917 | err = __check_map_access(env, regno, reg->umax_value + off, size); |
f1174f77 EC |
918 | if (err) |
919 | verbose("R%d max value is outside of the array range\n", regno); | |
920 | return err; | |
dbcfe5f7 GB |
921 | } |
922 | ||
969bf05e AS |
923 | #define MAX_PACKET_OFF 0xffff |
924 | ||
58e2af8b | 925 | static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, |
3a0af8fd TG |
926 | const struct bpf_call_arg_meta *meta, |
927 | enum bpf_access_type t) | |
4acf6c0b | 928 | { |
36bbef52 | 929 | switch (env->prog->type) { |
3a0af8fd TG |
930 | case BPF_PROG_TYPE_LWT_IN: |
931 | case BPF_PROG_TYPE_LWT_OUT: | |
932 | /* dst_input() and dst_output() can't write for now */ | |
933 | if (t == BPF_WRITE) | |
934 | return false; | |
7e57fbb2 | 935 | /* fallthrough */ |
36bbef52 DB |
936 | case BPF_PROG_TYPE_SCHED_CLS: |
937 | case BPF_PROG_TYPE_SCHED_ACT: | |
4acf6c0b | 938 | case BPF_PROG_TYPE_XDP: |
3a0af8fd | 939 | case BPF_PROG_TYPE_LWT_XMIT: |
8a31db56 | 940 | case BPF_PROG_TYPE_SK_SKB: |
36bbef52 DB |
941 | if (meta) |
942 | return meta->pkt_access; | |
943 | ||
944 | env->seen_direct_write = true; | |
4acf6c0b BB |
945 | return true; |
946 | default: | |
947 | return false; | |
948 | } | |
949 | } | |
950 | ||
f1174f77 EC |
951 | static int __check_packet_access(struct bpf_verifier_env *env, u32 regno, |
952 | int off, int size) | |
969bf05e | 953 | { |
58e2af8b JK |
954 | struct bpf_reg_state *regs = env->cur_state.regs; |
955 | struct bpf_reg_state *reg = ®s[regno]; | |
969bf05e | 956 | |
f1174f77 | 957 | if (off < 0 || size <= 0 || (u64)off + size > reg->range) { |
d91b28ed AS |
958 | verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", |
959 | off, size, regno, reg->id, reg->off, reg->range); | |
969bf05e AS |
960 | return -EACCES; |
961 | } | |
962 | return 0; | |
963 | } | |
964 | ||
f1174f77 EC |
965 | static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, |
966 | int size) | |
967 | { | |
968 | struct bpf_reg_state *regs = env->cur_state.regs; | |
969 | struct bpf_reg_state *reg = ®s[regno]; | |
970 | int err; | |
971 | ||
972 | /* We may have added a variable offset to the packet pointer; but any | |
973 | * reg->range we have comes after that. We are only checking the fixed | |
974 | * offset. | |
975 | */ | |
976 | ||
977 | /* We don't allow negative numbers, because we aren't tracking enough | |
978 | * detail to prove they're safe. | |
979 | */ | |
b03c9f9f | 980 | if (reg->smin_value < 0) { |
f1174f77 EC |
981 | verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", |
982 | regno); | |
983 | return -EACCES; | |
984 | } | |
985 | err = __check_packet_access(env, regno, off, size); | |
986 | if (err) { | |
987 | verbose("R%d offset is outside of the packet\n", regno); | |
988 | return err; | |
989 | } | |
990 | return err; | |
991 | } | |
992 | ||
993 | /* check access to 'struct bpf_context' fields. Supports fixed offsets only */ | |
31fd8581 | 994 | static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, |
19de99f7 | 995 | enum bpf_access_type t, enum bpf_reg_type *reg_type) |
17a52670 | 996 | { |
f96da094 DB |
997 | struct bpf_insn_access_aux info = { |
998 | .reg_type = *reg_type, | |
999 | }; | |
31fd8581 | 1000 | |
13a27dfc JK |
1001 | /* for analyzer ctx accesses are already validated and converted */ |
1002 | if (env->analyzer_ops) | |
1003 | return 0; | |
1004 | ||
17a52670 | 1005 | if (env->prog->aux->ops->is_valid_access && |
23994631 | 1006 | env->prog->aux->ops->is_valid_access(off, size, t, &info)) { |
f96da094 DB |
1007 | /* A non zero info.ctx_field_size indicates that this field is a |
1008 | * candidate for later verifier transformation to load the whole | |
1009 | * field and then apply a mask when accessed with a narrower | |
1010 | * access than actual ctx access size. A zero info.ctx_field_size | |
1011 | * will only allow for whole field access and rejects any other | |
1012 | * type of narrower access. | |
31fd8581 | 1013 | */ |
f96da094 | 1014 | env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; |
23994631 | 1015 | *reg_type = info.reg_type; |
31fd8581 | 1016 | |
32bbe007 AS |
1017 | /* remember the offset of last byte accessed in ctx */ |
1018 | if (env->prog->aux->max_ctx_offset < off + size) | |
1019 | env->prog->aux->max_ctx_offset = off + size; | |
17a52670 | 1020 | return 0; |
32bbe007 | 1021 | } |
17a52670 AS |
1022 | |
1023 | verbose("invalid bpf_context access off=%d size=%d\n", off, size); | |
1024 | return -EACCES; | |
1025 | } | |
1026 | ||
4cabc5b1 DB |
1027 | static bool __is_pointer_value(bool allow_ptr_leaks, |
1028 | const struct bpf_reg_state *reg) | |
1be7f75d | 1029 | { |
4cabc5b1 | 1030 | if (allow_ptr_leaks) |
1be7f75d AS |
1031 | return false; |
1032 | ||
f1174f77 | 1033 | return reg->type != SCALAR_VALUE; |
1be7f75d AS |
1034 | } |
1035 | ||
4cabc5b1 DB |
1036 | static bool is_pointer_value(struct bpf_verifier_env *env, int regno) |
1037 | { | |
1038 | return __is_pointer_value(env->allow_ptr_leaks, &env->cur_state.regs[regno]); | |
1039 | } | |
1040 | ||
79adffcd | 1041 | static int check_pkt_ptr_alignment(const struct bpf_reg_state *reg, |
d1174416 | 1042 | int off, int size, bool strict) |
969bf05e | 1043 | { |
f1174f77 | 1044 | struct tnum reg_off; |
e07b98d9 | 1045 | int ip_align; |
d1174416 DM |
1046 | |
1047 | /* Byte size accesses are always allowed. */ | |
1048 | if (!strict || size == 1) | |
1049 | return 0; | |
1050 | ||
e4eda884 DM |
1051 | /* For platforms that do not have a Kconfig enabling |
1052 | * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of | |
1053 | * NET_IP_ALIGN is universally set to '2'. And on platforms | |
1054 | * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get | |
1055 | * to this code only in strict mode where we want to emulate | |
1056 | * the NET_IP_ALIGN==2 checking. Therefore use an | |
1057 | * unconditional IP align value of '2'. | |
e07b98d9 | 1058 | */ |
e4eda884 | 1059 | ip_align = 2; |
f1174f77 EC |
1060 | |
1061 | reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off)); | |
1062 | if (!tnum_is_aligned(reg_off, size)) { | |
1063 | char tn_buf[48]; | |
1064 | ||
1065 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
1066 | verbose("misaligned packet access off %d+%s+%d+%d size %d\n", | |
1067 | ip_align, tn_buf, reg->off, off, size); | |
969bf05e AS |
1068 | return -EACCES; |
1069 | } | |
79adffcd | 1070 | |
969bf05e AS |
1071 | return 0; |
1072 | } | |
1073 | ||
f1174f77 EC |
1074 | static int check_generic_ptr_alignment(const struct bpf_reg_state *reg, |
1075 | const char *pointer_desc, | |
1076 | int off, int size, bool strict) | |
79adffcd | 1077 | { |
f1174f77 EC |
1078 | struct tnum reg_off; |
1079 | ||
1080 | /* Byte size accesses are always allowed. */ | |
1081 | if (!strict || size == 1) | |
1082 | return 0; | |
1083 | ||
1084 | reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off)); | |
1085 | if (!tnum_is_aligned(reg_off, size)) { | |
1086 | char tn_buf[48]; | |
1087 | ||
1088 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
1089 | verbose("misaligned %saccess off %s+%d+%d size %d\n", | |
1090 | pointer_desc, tn_buf, reg->off, off, size); | |
79adffcd DB |
1091 | return -EACCES; |
1092 | } | |
1093 | ||
969bf05e AS |
1094 | return 0; |
1095 | } | |
1096 | ||
e07b98d9 DM |
1097 | static int check_ptr_alignment(struct bpf_verifier_env *env, |
1098 | const struct bpf_reg_state *reg, | |
79adffcd DB |
1099 | int off, int size) |
1100 | { | |
e07b98d9 | 1101 | bool strict = env->strict_alignment; |
f1174f77 | 1102 | const char *pointer_desc = ""; |
d1174416 | 1103 | |
79adffcd DB |
1104 | switch (reg->type) { |
1105 | case PTR_TO_PACKET: | |
de8f3a83 DB |
1106 | case PTR_TO_PACKET_META: |
1107 | /* Special case, because of NET_IP_ALIGN. Given metadata sits | |
1108 | * right in front, treat it the very same way. | |
1109 | */ | |
d1174416 | 1110 | return check_pkt_ptr_alignment(reg, off, size, strict); |
f1174f77 EC |
1111 | case PTR_TO_MAP_VALUE: |
1112 | pointer_desc = "value "; | |
1113 | break; | |
1114 | case PTR_TO_CTX: | |
1115 | pointer_desc = "context "; | |
1116 | break; | |
1117 | case PTR_TO_STACK: | |
1118 | pointer_desc = "stack "; | |
1119 | break; | |
79adffcd | 1120 | default: |
f1174f77 | 1121 | break; |
79adffcd | 1122 | } |
f1174f77 | 1123 | return check_generic_ptr_alignment(reg, pointer_desc, off, size, strict); |
79adffcd DB |
1124 | } |
1125 | ||
17a52670 AS |
1126 | /* check whether memory at (regno + off) is accessible for t = (read | write) |
1127 | * if t==write, value_regno is a register which value is stored into memory | |
1128 | * if t==read, value_regno is a register which will receive the value from memory | |
1129 | * if t==write && value_regno==-1, some unknown value is stored into memory | |
1130 | * if t==read && value_regno==-1, don't care what we read from memory | |
1131 | */ | |
31fd8581 | 1132 | static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, |
17a52670 AS |
1133 | int bpf_size, enum bpf_access_type t, |
1134 | int value_regno) | |
1135 | { | |
58e2af8b JK |
1136 | struct bpf_verifier_state *state = &env->cur_state; |
1137 | struct bpf_reg_state *reg = &state->regs[regno]; | |
17a52670 AS |
1138 | int size, err = 0; |
1139 | ||
1140 | size = bpf_size_to_bytes(bpf_size); | |
1141 | if (size < 0) | |
1142 | return size; | |
1143 | ||
f1174f77 | 1144 | /* alignment checks will add in reg->off themselves */ |
e07b98d9 | 1145 | err = check_ptr_alignment(env, reg, off, size); |
969bf05e AS |
1146 | if (err) |
1147 | return err; | |
17a52670 | 1148 | |
f1174f77 EC |
1149 | /* for access checks, reg->off is just part of off */ |
1150 | off += reg->off; | |
1151 | ||
1152 | if (reg->type == PTR_TO_MAP_VALUE) { | |
1be7f75d AS |
1153 | if (t == BPF_WRITE && value_regno >= 0 && |
1154 | is_pointer_value(env, value_regno)) { | |
1155 | verbose("R%d leaks addr into map\n", value_regno); | |
1156 | return -EACCES; | |
1157 | } | |
48461135 | 1158 | |
f1174f77 | 1159 | err = check_map_access(env, regno, off, size); |
17a52670 | 1160 | if (!err && t == BPF_READ && value_regno >= 0) |
f1174f77 | 1161 | mark_reg_unknown(state->regs, value_regno); |
17a52670 | 1162 | |
1a0dc1ac | 1163 | } else if (reg->type == PTR_TO_CTX) { |
f1174f77 | 1164 | enum bpf_reg_type reg_type = SCALAR_VALUE; |
19de99f7 | 1165 | |
1be7f75d AS |
1166 | if (t == BPF_WRITE && value_regno >= 0 && |
1167 | is_pointer_value(env, value_regno)) { | |
1168 | verbose("R%d leaks addr into ctx\n", value_regno); | |
1169 | return -EACCES; | |
1170 | } | |
f1174f77 EC |
1171 | /* ctx accesses must be at a fixed offset, so that we can |
1172 | * determine what type of data were returned. | |
1173 | */ | |
1174 | if (!tnum_is_const(reg->var_off)) { | |
1175 | char tn_buf[48]; | |
1176 | ||
1177 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
1178 | verbose("variable ctx access var_off=%s off=%d size=%d", | |
1179 | tn_buf, off, size); | |
1180 | return -EACCES; | |
1181 | } | |
1182 | off += reg->var_off.value; | |
31fd8581 | 1183 | err = check_ctx_access(env, insn_idx, off, size, t, ®_type); |
969bf05e | 1184 | if (!err && t == BPF_READ && value_regno >= 0) { |
f1174f77 | 1185 | /* ctx access returns either a scalar, or a |
de8f3a83 DB |
1186 | * PTR_TO_PACKET[_META,_END]. In the latter |
1187 | * case, we know the offset is zero. | |
f1174f77 EC |
1188 | */ |
1189 | if (reg_type == SCALAR_VALUE) | |
1190 | mark_reg_unknown(state->regs, value_regno); | |
1191 | else | |
1192 | mark_reg_known_zero(state->regs, value_regno); | |
1193 | state->regs[value_regno].id = 0; | |
1194 | state->regs[value_regno].off = 0; | |
1195 | state->regs[value_regno].range = 0; | |
1955351d | 1196 | state->regs[value_regno].type = reg_type; |
969bf05e | 1197 | } |
17a52670 | 1198 | |
f1174f77 EC |
1199 | } else if (reg->type == PTR_TO_STACK) { |
1200 | /* stack accesses must be at a fixed offset, so that we can | |
1201 | * determine what type of data were returned. | |
1202 | * See check_stack_read(). | |
1203 | */ | |
1204 | if (!tnum_is_const(reg->var_off)) { | |
1205 | char tn_buf[48]; | |
1206 | ||
1207 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
1208 | verbose("variable stack access var_off=%s off=%d size=%d", | |
1209 | tn_buf, off, size); | |
1210 | return -EACCES; | |
1211 | } | |
1212 | off += reg->var_off.value; | |
17a52670 AS |
1213 | if (off >= 0 || off < -MAX_BPF_STACK) { |
1214 | verbose("invalid stack off=%d size=%d\n", off, size); | |
1215 | return -EACCES; | |
1216 | } | |
8726679a AS |
1217 | |
1218 | if (env->prog->aux->stack_depth < -off) | |
1219 | env->prog->aux->stack_depth = -off; | |
1220 | ||
1be7f75d AS |
1221 | if (t == BPF_WRITE) { |
1222 | if (!env->allow_ptr_leaks && | |
1223 | state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && | |
1224 | size != BPF_REG_SIZE) { | |
1225 | verbose("attempt to corrupt spilled pointer on stack\n"); | |
1226 | return -EACCES; | |
1227 | } | |
17a52670 | 1228 | err = check_stack_write(state, off, size, value_regno); |
1be7f75d | 1229 | } else { |
17a52670 | 1230 | err = check_stack_read(state, off, size, value_regno); |
1be7f75d | 1231 | } |
de8f3a83 | 1232 | } else if (reg_is_pkt_pointer(reg)) { |
3a0af8fd | 1233 | if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { |
969bf05e AS |
1234 | verbose("cannot write into packet\n"); |
1235 | return -EACCES; | |
1236 | } | |
4acf6c0b BB |
1237 | if (t == BPF_WRITE && value_regno >= 0 && |
1238 | is_pointer_value(env, value_regno)) { | |
1239 | verbose("R%d leaks addr into packet\n", value_regno); | |
1240 | return -EACCES; | |
1241 | } | |
969bf05e AS |
1242 | err = check_packet_access(env, regno, off, size); |
1243 | if (!err && t == BPF_READ && value_regno >= 0) | |
f1174f77 | 1244 | mark_reg_unknown(state->regs, value_regno); |
17a52670 AS |
1245 | } else { |
1246 | verbose("R%d invalid mem access '%s'\n", | |
1a0dc1ac | 1247 | regno, reg_type_str[reg->type]); |
17a52670 AS |
1248 | return -EACCES; |
1249 | } | |
969bf05e | 1250 | |
f1174f77 EC |
1251 | if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ && |
1252 | state->regs[value_regno].type == SCALAR_VALUE) { | |
1253 | /* b/h/w load zero-extends, mark upper bits as known 0 */ | |
1254 | state->regs[value_regno].var_off = tnum_cast( | |
1255 | state->regs[value_regno].var_off, size); | |
b03c9f9f | 1256 | __update_reg_bounds(&state->regs[value_regno]); |
969bf05e | 1257 | } |
17a52670 AS |
1258 | return err; |
1259 | } | |
1260 | ||
31fd8581 | 1261 | static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) |
17a52670 | 1262 | { |
17a52670 AS |
1263 | int err; |
1264 | ||
1265 | if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || | |
1266 | insn->imm != 0) { | |
1267 | verbose("BPF_XADD uses reserved fields\n"); | |
1268 | return -EINVAL; | |
1269 | } | |
1270 | ||
1271 | /* check src1 operand */ | |
dc503a8a | 1272 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
1273 | if (err) |
1274 | return err; | |
1275 | ||
1276 | /* check src2 operand */ | |
dc503a8a | 1277 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
1278 | if (err) |
1279 | return err; | |
1280 | ||
6bdf6abc DB |
1281 | if (is_pointer_value(env, insn->src_reg)) { |
1282 | verbose("R%d leaks addr into mem\n", insn->src_reg); | |
1283 | return -EACCES; | |
1284 | } | |
1285 | ||
17a52670 | 1286 | /* check whether atomic_add can read the memory */ |
31fd8581 | 1287 | err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
1288 | BPF_SIZE(insn->code), BPF_READ, -1); |
1289 | if (err) | |
1290 | return err; | |
1291 | ||
1292 | /* check whether atomic_add can write into the same memory */ | |
31fd8581 | 1293 | return check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
1294 | BPF_SIZE(insn->code), BPF_WRITE, -1); |
1295 | } | |
1296 | ||
f1174f77 EC |
1297 | /* Does this register contain a constant zero? */ |
1298 | static bool register_is_null(struct bpf_reg_state reg) | |
1299 | { | |
1300 | return reg.type == SCALAR_VALUE && tnum_equals_const(reg.var_off, 0); | |
1301 | } | |
1302 | ||
17a52670 AS |
1303 | /* when register 'regno' is passed into function that will read 'access_size' |
1304 | * bytes from that pointer, make sure that it's within stack boundary | |
f1174f77 EC |
1305 | * and all elements of stack are initialized. |
1306 | * Unlike most pointer bounds-checking functions, this one doesn't take an | |
1307 | * 'off' argument, so it has to add in reg->off itself. | |
17a52670 | 1308 | */ |
58e2af8b | 1309 | static int check_stack_boundary(struct bpf_verifier_env *env, int regno, |
435faee1 DB |
1310 | int access_size, bool zero_size_allowed, |
1311 | struct bpf_call_arg_meta *meta) | |
17a52670 | 1312 | { |
58e2af8b JK |
1313 | struct bpf_verifier_state *state = &env->cur_state; |
1314 | struct bpf_reg_state *regs = state->regs; | |
17a52670 AS |
1315 | int off, i; |
1316 | ||
8e2fe1d9 | 1317 | if (regs[regno].type != PTR_TO_STACK) { |
f1174f77 | 1318 | /* Allow zero-byte read from NULL, regardless of pointer type */ |
8e2fe1d9 | 1319 | if (zero_size_allowed && access_size == 0 && |
f1174f77 | 1320 | register_is_null(regs[regno])) |
8e2fe1d9 DB |
1321 | return 0; |
1322 | ||
1323 | verbose("R%d type=%s expected=%s\n", regno, | |
1324 | reg_type_str[regs[regno].type], | |
1325 | reg_type_str[PTR_TO_STACK]); | |
17a52670 | 1326 | return -EACCES; |
8e2fe1d9 | 1327 | } |
17a52670 | 1328 | |
f1174f77 EC |
1329 | /* Only allow fixed-offset stack reads */ |
1330 | if (!tnum_is_const(regs[regno].var_off)) { | |
1331 | char tn_buf[48]; | |
1332 | ||
1333 | tnum_strn(tn_buf, sizeof(tn_buf), regs[regno].var_off); | |
1334 | verbose("invalid variable stack read R%d var_off=%s\n", | |
1335 | regno, tn_buf); | |
1336 | } | |
1337 | off = regs[regno].off + regs[regno].var_off.value; | |
17a52670 AS |
1338 | if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || |
1339 | access_size <= 0) { | |
1340 | verbose("invalid stack type R%d off=%d access_size=%d\n", | |
1341 | regno, off, access_size); | |
1342 | return -EACCES; | |
1343 | } | |
1344 | ||
8726679a AS |
1345 | if (env->prog->aux->stack_depth < -off) |
1346 | env->prog->aux->stack_depth = -off; | |
1347 | ||
435faee1 DB |
1348 | if (meta && meta->raw_mode) { |
1349 | meta->access_size = access_size; | |
1350 | meta->regno = regno; | |
1351 | return 0; | |
1352 | } | |
1353 | ||
17a52670 | 1354 | for (i = 0; i < access_size; i++) { |
9c399760 | 1355 | if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { |
17a52670 AS |
1356 | verbose("invalid indirect read from stack off %d+%d size %d\n", |
1357 | off, i, access_size); | |
1358 | return -EACCES; | |
1359 | } | |
1360 | } | |
1361 | return 0; | |
1362 | } | |
1363 | ||
06c1c049 GB |
1364 | static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, |
1365 | int access_size, bool zero_size_allowed, | |
1366 | struct bpf_call_arg_meta *meta) | |
1367 | { | |
f1174f77 | 1368 | struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; |
06c1c049 | 1369 | |
f1174f77 | 1370 | switch (reg->type) { |
06c1c049 | 1371 | case PTR_TO_PACKET: |
de8f3a83 | 1372 | case PTR_TO_PACKET_META: |
f1174f77 | 1373 | return check_packet_access(env, regno, reg->off, access_size); |
06c1c049 | 1374 | case PTR_TO_MAP_VALUE: |
f1174f77 EC |
1375 | return check_map_access(env, regno, reg->off, access_size); |
1376 | default: /* scalar_value|ptr_to_stack or invalid ptr */ | |
06c1c049 GB |
1377 | return check_stack_boundary(env, regno, access_size, |
1378 | zero_size_allowed, meta); | |
1379 | } | |
1380 | } | |
1381 | ||
58e2af8b | 1382 | static int check_func_arg(struct bpf_verifier_env *env, u32 regno, |
33ff9823 DB |
1383 | enum bpf_arg_type arg_type, |
1384 | struct bpf_call_arg_meta *meta) | |
17a52670 | 1385 | { |
58e2af8b | 1386 | struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; |
6841de8b | 1387 | enum bpf_reg_type expected_type, type = reg->type; |
17a52670 AS |
1388 | int err = 0; |
1389 | ||
80f1d68c | 1390 | if (arg_type == ARG_DONTCARE) |
17a52670 AS |
1391 | return 0; |
1392 | ||
dc503a8a EC |
1393 | err = check_reg_arg(env, regno, SRC_OP); |
1394 | if (err) | |
1395 | return err; | |
17a52670 | 1396 | |
1be7f75d AS |
1397 | if (arg_type == ARG_ANYTHING) { |
1398 | if (is_pointer_value(env, regno)) { | |
1399 | verbose("R%d leaks addr into helper function\n", regno); | |
1400 | return -EACCES; | |
1401 | } | |
80f1d68c | 1402 | return 0; |
1be7f75d | 1403 | } |
80f1d68c | 1404 | |
de8f3a83 | 1405 | if (type_is_pkt_pointer(type) && |
3a0af8fd | 1406 | !may_access_direct_pkt_data(env, meta, BPF_READ)) { |
36bbef52 | 1407 | verbose("helper access to the packet is not allowed\n"); |
6841de8b AS |
1408 | return -EACCES; |
1409 | } | |
1410 | ||
8e2fe1d9 | 1411 | if (arg_type == ARG_PTR_TO_MAP_KEY || |
17a52670 AS |
1412 | arg_type == ARG_PTR_TO_MAP_VALUE) { |
1413 | expected_type = PTR_TO_STACK; | |
de8f3a83 DB |
1414 | if (!type_is_pkt_pointer(type) && |
1415 | type != expected_type) | |
6841de8b | 1416 | goto err_type; |
39f19ebb AS |
1417 | } else if (arg_type == ARG_CONST_SIZE || |
1418 | arg_type == ARG_CONST_SIZE_OR_ZERO) { | |
f1174f77 EC |
1419 | expected_type = SCALAR_VALUE; |
1420 | if (type != expected_type) | |
6841de8b | 1421 | goto err_type; |
17a52670 AS |
1422 | } else if (arg_type == ARG_CONST_MAP_PTR) { |
1423 | expected_type = CONST_PTR_TO_MAP; | |
6841de8b AS |
1424 | if (type != expected_type) |
1425 | goto err_type; | |
608cd71a AS |
1426 | } else if (arg_type == ARG_PTR_TO_CTX) { |
1427 | expected_type = PTR_TO_CTX; | |
6841de8b AS |
1428 | if (type != expected_type) |
1429 | goto err_type; | |
39f19ebb AS |
1430 | } else if (arg_type == ARG_PTR_TO_MEM || |
1431 | arg_type == ARG_PTR_TO_UNINIT_MEM) { | |
8e2fe1d9 DB |
1432 | expected_type = PTR_TO_STACK; |
1433 | /* One exception here. In case function allows for NULL to be | |
f1174f77 | 1434 | * passed in as argument, it's a SCALAR_VALUE type. Final test |
8e2fe1d9 DB |
1435 | * happens during stack boundary checking. |
1436 | */ | |
f1174f77 | 1437 | if (register_is_null(*reg)) |
6841de8b | 1438 | /* final test in check_stack_boundary() */; |
de8f3a83 DB |
1439 | else if (!type_is_pkt_pointer(type) && |
1440 | type != PTR_TO_MAP_VALUE && | |
f1174f77 | 1441 | type != expected_type) |
6841de8b | 1442 | goto err_type; |
39f19ebb | 1443 | meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM; |
17a52670 AS |
1444 | } else { |
1445 | verbose("unsupported arg_type %d\n", arg_type); | |
1446 | return -EFAULT; | |
1447 | } | |
1448 | ||
17a52670 AS |
1449 | if (arg_type == ARG_CONST_MAP_PTR) { |
1450 | /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ | |
33ff9823 | 1451 | meta->map_ptr = reg->map_ptr; |
17a52670 AS |
1452 | } else if (arg_type == ARG_PTR_TO_MAP_KEY) { |
1453 | /* bpf_map_xxx(..., map_ptr, ..., key) call: | |
1454 | * check that [key, key + map->key_size) are within | |
1455 | * stack limits and initialized | |
1456 | */ | |
33ff9823 | 1457 | if (!meta->map_ptr) { |
17a52670 AS |
1458 | /* in function declaration map_ptr must come before |
1459 | * map_key, so that it's verified and known before | |
1460 | * we have to check map_key here. Otherwise it means | |
1461 | * that kernel subsystem misconfigured verifier | |
1462 | */ | |
1463 | verbose("invalid map_ptr to access map->key\n"); | |
1464 | return -EACCES; | |
1465 | } | |
de8f3a83 | 1466 | if (type_is_pkt_pointer(type)) |
f1174f77 | 1467 | err = check_packet_access(env, regno, reg->off, |
6841de8b AS |
1468 | meta->map_ptr->key_size); |
1469 | else | |
1470 | err = check_stack_boundary(env, regno, | |
1471 | meta->map_ptr->key_size, | |
1472 | false, NULL); | |
17a52670 AS |
1473 | } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { |
1474 | /* bpf_map_xxx(..., map_ptr, ..., value) call: | |
1475 | * check [value, value + map->value_size) validity | |
1476 | */ | |
33ff9823 | 1477 | if (!meta->map_ptr) { |
17a52670 AS |
1478 | /* kernel subsystem misconfigured verifier */ |
1479 | verbose("invalid map_ptr to access map->value\n"); | |
1480 | return -EACCES; | |
1481 | } | |
de8f3a83 | 1482 | if (type_is_pkt_pointer(type)) |
f1174f77 | 1483 | err = check_packet_access(env, regno, reg->off, |
6841de8b AS |
1484 | meta->map_ptr->value_size); |
1485 | else | |
1486 | err = check_stack_boundary(env, regno, | |
1487 | meta->map_ptr->value_size, | |
1488 | false, NULL); | |
39f19ebb AS |
1489 | } else if (arg_type == ARG_CONST_SIZE || |
1490 | arg_type == ARG_CONST_SIZE_OR_ZERO) { | |
1491 | bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); | |
17a52670 | 1492 | |
17a52670 AS |
1493 | /* bpf_xxx(..., buf, len) call will access 'len' bytes |
1494 | * from stack pointer 'buf'. Check it | |
1495 | * note: regno == len, regno - 1 == buf | |
1496 | */ | |
1497 | if (regno == 0) { | |
1498 | /* kernel subsystem misconfigured verifier */ | |
39f19ebb | 1499 | verbose("ARG_CONST_SIZE cannot be first argument\n"); |
17a52670 AS |
1500 | return -EACCES; |
1501 | } | |
06c1c049 | 1502 | |
f1174f77 EC |
1503 | /* The register is SCALAR_VALUE; the access check |
1504 | * happens using its boundaries. | |
06c1c049 | 1505 | */ |
f1174f77 EC |
1506 | |
1507 | if (!tnum_is_const(reg->var_off)) | |
06c1c049 GB |
1508 | /* For unprivileged variable accesses, disable raw |
1509 | * mode so that the program is required to | |
1510 | * initialize all the memory that the helper could | |
1511 | * just partially fill up. | |
1512 | */ | |
1513 | meta = NULL; | |
1514 | ||
b03c9f9f | 1515 | if (reg->smin_value < 0) { |
f1174f77 EC |
1516 | verbose("R%d min value is negative, either use unsigned or 'var &= const'\n", |
1517 | regno); | |
1518 | return -EACCES; | |
1519 | } | |
06c1c049 | 1520 | |
b03c9f9f | 1521 | if (reg->umin_value == 0) { |
f1174f77 EC |
1522 | err = check_helper_mem_access(env, regno - 1, 0, |
1523 | zero_size_allowed, | |
1524 | meta); | |
06c1c049 GB |
1525 | if (err) |
1526 | return err; | |
06c1c049 | 1527 | } |
f1174f77 | 1528 | |
b03c9f9f | 1529 | if (reg->umax_value >= BPF_MAX_VAR_SIZ) { |
f1174f77 EC |
1530 | verbose("R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", |
1531 | regno); | |
1532 | return -EACCES; | |
1533 | } | |
1534 | err = check_helper_mem_access(env, regno - 1, | |
b03c9f9f | 1535 | reg->umax_value, |
f1174f77 | 1536 | zero_size_allowed, meta); |
17a52670 AS |
1537 | } |
1538 | ||
1539 | return err; | |
6841de8b AS |
1540 | err_type: |
1541 | verbose("R%d type=%s expected=%s\n", regno, | |
1542 | reg_type_str[type], reg_type_str[expected_type]); | |
1543 | return -EACCES; | |
17a52670 AS |
1544 | } |
1545 | ||
35578d79 KX |
1546 | static int check_map_func_compatibility(struct bpf_map *map, int func_id) |
1547 | { | |
35578d79 KX |
1548 | if (!map) |
1549 | return 0; | |
1550 | ||
6aff67c8 AS |
1551 | /* We need a two way check, first is from map perspective ... */ |
1552 | switch (map->map_type) { | |
1553 | case BPF_MAP_TYPE_PROG_ARRAY: | |
1554 | if (func_id != BPF_FUNC_tail_call) | |
1555 | goto error; | |
1556 | break; | |
1557 | case BPF_MAP_TYPE_PERF_EVENT_ARRAY: | |
1558 | if (func_id != BPF_FUNC_perf_event_read && | |
908432ca YS |
1559 | func_id != BPF_FUNC_perf_event_output && |
1560 | func_id != BPF_FUNC_perf_event_read_value) | |
6aff67c8 AS |
1561 | goto error; |
1562 | break; | |
1563 | case BPF_MAP_TYPE_STACK_TRACE: | |
1564 | if (func_id != BPF_FUNC_get_stackid) | |
1565 | goto error; | |
1566 | break; | |
4ed8ec52 | 1567 | case BPF_MAP_TYPE_CGROUP_ARRAY: |
60747ef4 | 1568 | if (func_id != BPF_FUNC_skb_under_cgroup && |
60d20f91 | 1569 | func_id != BPF_FUNC_current_task_under_cgroup) |
4a482f34 MKL |
1570 | goto error; |
1571 | break; | |
546ac1ff JF |
1572 | /* devmap returns a pointer to a live net_device ifindex that we cannot |
1573 | * allow to be modified from bpf side. So do not allow lookup elements | |
1574 | * for now. | |
1575 | */ | |
1576 | case BPF_MAP_TYPE_DEVMAP: | |
2ddf71e2 | 1577 | if (func_id != BPF_FUNC_redirect_map) |
546ac1ff JF |
1578 | goto error; |
1579 | break; | |
56f668df | 1580 | case BPF_MAP_TYPE_ARRAY_OF_MAPS: |
bcc6b1b7 | 1581 | case BPF_MAP_TYPE_HASH_OF_MAPS: |
56f668df MKL |
1582 | if (func_id != BPF_FUNC_map_lookup_elem) |
1583 | goto error; | |
16a43625 | 1584 | break; |
174a79ff JF |
1585 | case BPF_MAP_TYPE_SOCKMAP: |
1586 | if (func_id != BPF_FUNC_sk_redirect_map && | |
1587 | func_id != BPF_FUNC_sock_map_update && | |
1588 | func_id != BPF_FUNC_map_delete_elem) | |
1589 | goto error; | |
1590 | break; | |
6aff67c8 AS |
1591 | default: |
1592 | break; | |
1593 | } | |
1594 | ||
1595 | /* ... and second from the function itself. */ | |
1596 | switch (func_id) { | |
1597 | case BPF_FUNC_tail_call: | |
1598 | if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) | |
1599 | goto error; | |
1600 | break; | |
1601 | case BPF_FUNC_perf_event_read: | |
1602 | case BPF_FUNC_perf_event_output: | |
908432ca | 1603 | case BPF_FUNC_perf_event_read_value: |
6aff67c8 AS |
1604 | if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) |
1605 | goto error; | |
1606 | break; | |
1607 | case BPF_FUNC_get_stackid: | |
1608 | if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) | |
1609 | goto error; | |
1610 | break; | |
60d20f91 | 1611 | case BPF_FUNC_current_task_under_cgroup: |
747ea55e | 1612 | case BPF_FUNC_skb_under_cgroup: |
4a482f34 MKL |
1613 | if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) |
1614 | goto error; | |
1615 | break; | |
97f91a7c JF |
1616 | case BPF_FUNC_redirect_map: |
1617 | if (map->map_type != BPF_MAP_TYPE_DEVMAP) | |
1618 | goto error; | |
1619 | break; | |
174a79ff JF |
1620 | case BPF_FUNC_sk_redirect_map: |
1621 | if (map->map_type != BPF_MAP_TYPE_SOCKMAP) | |
1622 | goto error; | |
1623 | break; | |
1624 | case BPF_FUNC_sock_map_update: | |
1625 | if (map->map_type != BPF_MAP_TYPE_SOCKMAP) | |
1626 | goto error; | |
1627 | break; | |
6aff67c8 AS |
1628 | default: |
1629 | break; | |
35578d79 KX |
1630 | } |
1631 | ||
1632 | return 0; | |
6aff67c8 | 1633 | error: |
ebb676da TG |
1634 | verbose("cannot pass map_type %d into func %s#%d\n", |
1635 | map->map_type, func_id_name(func_id), func_id); | |
6aff67c8 | 1636 | return -EINVAL; |
35578d79 KX |
1637 | } |
1638 | ||
435faee1 DB |
1639 | static int check_raw_mode(const struct bpf_func_proto *fn) |
1640 | { | |
1641 | int count = 0; | |
1642 | ||
39f19ebb | 1643 | if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1644 | count++; |
39f19ebb | 1645 | if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1646 | count++; |
39f19ebb | 1647 | if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1648 | count++; |
39f19ebb | 1649 | if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1650 | count++; |
39f19ebb | 1651 | if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 DB |
1652 | count++; |
1653 | ||
1654 | return count > 1 ? -EINVAL : 0; | |
1655 | } | |
1656 | ||
de8f3a83 DB |
1657 | /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END] |
1658 | * are now invalid, so turn them into unknown SCALAR_VALUE. | |
f1174f77 | 1659 | */ |
58e2af8b | 1660 | static void clear_all_pkt_pointers(struct bpf_verifier_env *env) |
969bf05e | 1661 | { |
58e2af8b JK |
1662 | struct bpf_verifier_state *state = &env->cur_state; |
1663 | struct bpf_reg_state *regs = state->regs, *reg; | |
969bf05e AS |
1664 | int i; |
1665 | ||
1666 | for (i = 0; i < MAX_BPF_REG; i++) | |
de8f3a83 | 1667 | if (reg_is_pkt_pointer_any(®s[i])) |
f1174f77 | 1668 | mark_reg_unknown(regs, i); |
969bf05e AS |
1669 | |
1670 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1671 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1672 | continue; | |
1673 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
de8f3a83 DB |
1674 | if (reg_is_pkt_pointer_any(reg)) |
1675 | __mark_reg_unknown(reg); | |
969bf05e AS |
1676 | } |
1677 | } | |
1678 | ||
81ed18ab | 1679 | static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx) |
17a52670 | 1680 | { |
58e2af8b | 1681 | struct bpf_verifier_state *state = &env->cur_state; |
17a52670 | 1682 | const struct bpf_func_proto *fn = NULL; |
58e2af8b | 1683 | struct bpf_reg_state *regs = state->regs; |
33ff9823 | 1684 | struct bpf_call_arg_meta meta; |
969bf05e | 1685 | bool changes_data; |
17a52670 AS |
1686 | int i, err; |
1687 | ||
1688 | /* find function prototype */ | |
1689 | if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { | |
ebb676da | 1690 | verbose("invalid func %s#%d\n", func_id_name(func_id), func_id); |
17a52670 AS |
1691 | return -EINVAL; |
1692 | } | |
1693 | ||
1694 | if (env->prog->aux->ops->get_func_proto) | |
1695 | fn = env->prog->aux->ops->get_func_proto(func_id); | |
1696 | ||
1697 | if (!fn) { | |
ebb676da | 1698 | verbose("unknown func %s#%d\n", func_id_name(func_id), func_id); |
17a52670 AS |
1699 | return -EINVAL; |
1700 | } | |
1701 | ||
1702 | /* eBPF programs must be GPL compatible to use GPL-ed functions */ | |
24701ece | 1703 | if (!env->prog->gpl_compatible && fn->gpl_only) { |
17a52670 AS |
1704 | verbose("cannot call GPL only function from proprietary program\n"); |
1705 | return -EINVAL; | |
1706 | } | |
1707 | ||
17bedab2 | 1708 | changes_data = bpf_helper_changes_pkt_data(fn->func); |
969bf05e | 1709 | |
33ff9823 | 1710 | memset(&meta, 0, sizeof(meta)); |
36bbef52 | 1711 | meta.pkt_access = fn->pkt_access; |
33ff9823 | 1712 | |
435faee1 DB |
1713 | /* We only support one arg being in raw mode at the moment, which |
1714 | * is sufficient for the helper functions we have right now. | |
1715 | */ | |
1716 | err = check_raw_mode(fn); | |
1717 | if (err) { | |
ebb676da TG |
1718 | verbose("kernel subsystem misconfigured func %s#%d\n", |
1719 | func_id_name(func_id), func_id); | |
435faee1 DB |
1720 | return err; |
1721 | } | |
1722 | ||
17a52670 | 1723 | /* check args */ |
33ff9823 | 1724 | err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); |
17a52670 AS |
1725 | if (err) |
1726 | return err; | |
33ff9823 | 1727 | err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); |
17a52670 AS |
1728 | if (err) |
1729 | return err; | |
33ff9823 | 1730 | err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); |
17a52670 AS |
1731 | if (err) |
1732 | return err; | |
33ff9823 | 1733 | err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); |
17a52670 AS |
1734 | if (err) |
1735 | return err; | |
33ff9823 | 1736 | err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); |
17a52670 AS |
1737 | if (err) |
1738 | return err; | |
1739 | ||
435faee1 DB |
1740 | /* Mark slots with STACK_MISC in case of raw mode, stack offset |
1741 | * is inferred from register state. | |
1742 | */ | |
1743 | for (i = 0; i < meta.access_size; i++) { | |
31fd8581 | 1744 | err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1); |
435faee1 DB |
1745 | if (err) |
1746 | return err; | |
1747 | } | |
1748 | ||
17a52670 | 1749 | /* reset caller saved regs */ |
dc503a8a | 1750 | for (i = 0; i < CALLER_SAVED_REGS; i++) { |
a9789ef9 | 1751 | mark_reg_not_init(regs, caller_saved[i]); |
dc503a8a EC |
1752 | check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); |
1753 | } | |
17a52670 | 1754 | |
dc503a8a | 1755 | /* update return register (already marked as written above) */ |
17a52670 | 1756 | if (fn->ret_type == RET_INTEGER) { |
f1174f77 EC |
1757 | /* sets type to SCALAR_VALUE */ |
1758 | mark_reg_unknown(regs, BPF_REG_0); | |
17a52670 AS |
1759 | } else if (fn->ret_type == RET_VOID) { |
1760 | regs[BPF_REG_0].type = NOT_INIT; | |
1761 | } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { | |
fad73a1a MKL |
1762 | struct bpf_insn_aux_data *insn_aux; |
1763 | ||
17a52670 | 1764 | regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; |
f1174f77 EC |
1765 | /* There is no offset yet applied, variable or fixed */ |
1766 | mark_reg_known_zero(regs, BPF_REG_0); | |
1767 | regs[BPF_REG_0].off = 0; | |
17a52670 AS |
1768 | /* remember map_ptr, so that check_map_access() |
1769 | * can check 'value_size' boundary of memory access | |
1770 | * to map element returned from bpf_map_lookup_elem() | |
1771 | */ | |
33ff9823 | 1772 | if (meta.map_ptr == NULL) { |
17a52670 AS |
1773 | verbose("kernel subsystem misconfigured verifier\n"); |
1774 | return -EINVAL; | |
1775 | } | |
33ff9823 | 1776 | regs[BPF_REG_0].map_ptr = meta.map_ptr; |
57a09bf0 | 1777 | regs[BPF_REG_0].id = ++env->id_gen; |
fad73a1a MKL |
1778 | insn_aux = &env->insn_aux_data[insn_idx]; |
1779 | if (!insn_aux->map_ptr) | |
1780 | insn_aux->map_ptr = meta.map_ptr; | |
1781 | else if (insn_aux->map_ptr != meta.map_ptr) | |
1782 | insn_aux->map_ptr = BPF_MAP_PTR_POISON; | |
17a52670 | 1783 | } else { |
ebb676da TG |
1784 | verbose("unknown return type %d of func %s#%d\n", |
1785 | fn->ret_type, func_id_name(func_id), func_id); | |
17a52670 AS |
1786 | return -EINVAL; |
1787 | } | |
04fd61ab | 1788 | |
33ff9823 | 1789 | err = check_map_func_compatibility(meta.map_ptr, func_id); |
35578d79 KX |
1790 | if (err) |
1791 | return err; | |
04fd61ab | 1792 | |
969bf05e AS |
1793 | if (changes_data) |
1794 | clear_all_pkt_pointers(env); | |
1795 | return 0; | |
1796 | } | |
1797 | ||
f1174f77 EC |
1798 | static void coerce_reg_to_32(struct bpf_reg_state *reg) |
1799 | { | |
f1174f77 EC |
1800 | /* clear high 32 bits */ |
1801 | reg->var_off = tnum_cast(reg->var_off, 4); | |
b03c9f9f EC |
1802 | /* Update bounds */ |
1803 | __update_reg_bounds(reg); | |
1804 | } | |
1805 | ||
1806 | static bool signed_add_overflows(s64 a, s64 b) | |
1807 | { | |
1808 | /* Do the add in u64, where overflow is well-defined */ | |
1809 | s64 res = (s64)((u64)a + (u64)b); | |
1810 | ||
1811 | if (b < 0) | |
1812 | return res > a; | |
1813 | return res < a; | |
1814 | } | |
1815 | ||
1816 | static bool signed_sub_overflows(s64 a, s64 b) | |
1817 | { | |
1818 | /* Do the sub in u64, where overflow is well-defined */ | |
1819 | s64 res = (s64)((u64)a - (u64)b); | |
1820 | ||
1821 | if (b < 0) | |
1822 | return res < a; | |
1823 | return res > a; | |
969bf05e AS |
1824 | } |
1825 | ||
f1174f77 | 1826 | /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off. |
f1174f77 EC |
1827 | * Caller should also handle BPF_MOV case separately. |
1828 | * If we return -EACCES, caller may want to try again treating pointer as a | |
1829 | * scalar. So we only emit a diagnostic if !env->allow_ptr_leaks. | |
1830 | */ | |
1831 | static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, | |
1832 | struct bpf_insn *insn, | |
1833 | const struct bpf_reg_state *ptr_reg, | |
1834 | const struct bpf_reg_state *off_reg) | |
969bf05e | 1835 | { |
f1174f77 EC |
1836 | struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; |
1837 | bool known = tnum_is_const(off_reg->var_off); | |
b03c9f9f EC |
1838 | s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value, |
1839 | smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value; | |
1840 | u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, | |
1841 | umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value; | |
969bf05e | 1842 | u8 opcode = BPF_OP(insn->code); |
f1174f77 | 1843 | u32 dst = insn->dst_reg; |
969bf05e | 1844 | |
f1174f77 | 1845 | dst_reg = ®s[dst]; |
969bf05e | 1846 | |
b03c9f9f | 1847 | if (WARN_ON_ONCE(known && (smin_val != smax_val))) { |
f1174f77 | 1848 | print_verifier_state(&env->cur_state); |
b03c9f9f EC |
1849 | verbose("verifier internal error: known but bad sbounds\n"); |
1850 | return -EINVAL; | |
1851 | } | |
1852 | if (WARN_ON_ONCE(known && (umin_val != umax_val))) { | |
1853 | print_verifier_state(&env->cur_state); | |
1854 | verbose("verifier internal error: known but bad ubounds\n"); | |
f1174f77 EC |
1855 | return -EINVAL; |
1856 | } | |
1857 | ||
1858 | if (BPF_CLASS(insn->code) != BPF_ALU64) { | |
1859 | /* 32-bit ALU ops on pointers produce (meaningless) scalars */ | |
1860 | if (!env->allow_ptr_leaks) | |
1861 | verbose("R%d 32-bit pointer arithmetic prohibited\n", | |
1862 | dst); | |
1863 | return -EACCES; | |
969bf05e AS |
1864 | } |
1865 | ||
f1174f77 EC |
1866 | if (ptr_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { |
1867 | if (!env->allow_ptr_leaks) | |
1868 | verbose("R%d pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL prohibited, null-check it first\n", | |
1869 | dst); | |
1870 | return -EACCES; | |
1871 | } | |
1872 | if (ptr_reg->type == CONST_PTR_TO_MAP) { | |
1873 | if (!env->allow_ptr_leaks) | |
1874 | verbose("R%d pointer arithmetic on CONST_PTR_TO_MAP prohibited\n", | |
1875 | dst); | |
1876 | return -EACCES; | |
1877 | } | |
1878 | if (ptr_reg->type == PTR_TO_PACKET_END) { | |
1879 | if (!env->allow_ptr_leaks) | |
1880 | verbose("R%d pointer arithmetic on PTR_TO_PACKET_END prohibited\n", | |
1881 | dst); | |
1882 | return -EACCES; | |
1883 | } | |
1884 | ||
1885 | /* In case of 'scalar += pointer', dst_reg inherits pointer type and id. | |
1886 | * The id may be overwritten later if we create a new variable offset. | |
969bf05e | 1887 | */ |
f1174f77 EC |
1888 | dst_reg->type = ptr_reg->type; |
1889 | dst_reg->id = ptr_reg->id; | |
969bf05e | 1890 | |
f1174f77 EC |
1891 | switch (opcode) { |
1892 | case BPF_ADD: | |
1893 | /* We can take a fixed offset as long as it doesn't overflow | |
1894 | * the s32 'off' field | |
969bf05e | 1895 | */ |
b03c9f9f EC |
1896 | if (known && (ptr_reg->off + smin_val == |
1897 | (s64)(s32)(ptr_reg->off + smin_val))) { | |
f1174f77 | 1898 | /* pointer += K. Accumulate it into fixed offset */ |
b03c9f9f EC |
1899 | dst_reg->smin_value = smin_ptr; |
1900 | dst_reg->smax_value = smax_ptr; | |
1901 | dst_reg->umin_value = umin_ptr; | |
1902 | dst_reg->umax_value = umax_ptr; | |
f1174f77 | 1903 | dst_reg->var_off = ptr_reg->var_off; |
b03c9f9f | 1904 | dst_reg->off = ptr_reg->off + smin_val; |
f1174f77 EC |
1905 | dst_reg->range = ptr_reg->range; |
1906 | break; | |
1907 | } | |
f1174f77 EC |
1908 | /* A new variable offset is created. Note that off_reg->off |
1909 | * == 0, since it's a scalar. | |
1910 | * dst_reg gets the pointer type and since some positive | |
1911 | * integer value was added to the pointer, give it a new 'id' | |
1912 | * if it's a PTR_TO_PACKET. | |
1913 | * this creates a new 'base' pointer, off_reg (variable) gets | |
1914 | * added into the variable offset, and we copy the fixed offset | |
1915 | * from ptr_reg. | |
969bf05e | 1916 | */ |
b03c9f9f EC |
1917 | if (signed_add_overflows(smin_ptr, smin_val) || |
1918 | signed_add_overflows(smax_ptr, smax_val)) { | |
1919 | dst_reg->smin_value = S64_MIN; | |
1920 | dst_reg->smax_value = S64_MAX; | |
1921 | } else { | |
1922 | dst_reg->smin_value = smin_ptr + smin_val; | |
1923 | dst_reg->smax_value = smax_ptr + smax_val; | |
1924 | } | |
1925 | if (umin_ptr + umin_val < umin_ptr || | |
1926 | umax_ptr + umax_val < umax_ptr) { | |
1927 | dst_reg->umin_value = 0; | |
1928 | dst_reg->umax_value = U64_MAX; | |
1929 | } else { | |
1930 | dst_reg->umin_value = umin_ptr + umin_val; | |
1931 | dst_reg->umax_value = umax_ptr + umax_val; | |
1932 | } | |
f1174f77 EC |
1933 | dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off); |
1934 | dst_reg->off = ptr_reg->off; | |
de8f3a83 | 1935 | if (reg_is_pkt_pointer(ptr_reg)) { |
f1174f77 EC |
1936 | dst_reg->id = ++env->id_gen; |
1937 | /* something was added to pkt_ptr, set range to zero */ | |
1938 | dst_reg->range = 0; | |
1939 | } | |
1940 | break; | |
1941 | case BPF_SUB: | |
1942 | if (dst_reg == off_reg) { | |
1943 | /* scalar -= pointer. Creates an unknown scalar */ | |
1944 | if (!env->allow_ptr_leaks) | |
1945 | verbose("R%d tried to subtract pointer from scalar\n", | |
1946 | dst); | |
1947 | return -EACCES; | |
1948 | } | |
1949 | /* We don't allow subtraction from FP, because (according to | |
1950 | * test_verifier.c test "invalid fp arithmetic", JITs might not | |
1951 | * be able to deal with it. | |
969bf05e | 1952 | */ |
f1174f77 EC |
1953 | if (ptr_reg->type == PTR_TO_STACK) { |
1954 | if (!env->allow_ptr_leaks) | |
1955 | verbose("R%d subtraction from stack pointer prohibited\n", | |
1956 | dst); | |
1957 | return -EACCES; | |
1958 | } | |
b03c9f9f EC |
1959 | if (known && (ptr_reg->off - smin_val == |
1960 | (s64)(s32)(ptr_reg->off - smin_val))) { | |
f1174f77 | 1961 | /* pointer -= K. Subtract it from fixed offset */ |
b03c9f9f EC |
1962 | dst_reg->smin_value = smin_ptr; |
1963 | dst_reg->smax_value = smax_ptr; | |
1964 | dst_reg->umin_value = umin_ptr; | |
1965 | dst_reg->umax_value = umax_ptr; | |
f1174f77 EC |
1966 | dst_reg->var_off = ptr_reg->var_off; |
1967 | dst_reg->id = ptr_reg->id; | |
b03c9f9f | 1968 | dst_reg->off = ptr_reg->off - smin_val; |
f1174f77 EC |
1969 | dst_reg->range = ptr_reg->range; |
1970 | break; | |
1971 | } | |
f1174f77 EC |
1972 | /* A new variable offset is created. If the subtrahend is known |
1973 | * nonnegative, then any reg->range we had before is still good. | |
969bf05e | 1974 | */ |
b03c9f9f EC |
1975 | if (signed_sub_overflows(smin_ptr, smax_val) || |
1976 | signed_sub_overflows(smax_ptr, smin_val)) { | |
1977 | /* Overflow possible, we know nothing */ | |
1978 | dst_reg->smin_value = S64_MIN; | |
1979 | dst_reg->smax_value = S64_MAX; | |
1980 | } else { | |
1981 | dst_reg->smin_value = smin_ptr - smax_val; | |
1982 | dst_reg->smax_value = smax_ptr - smin_val; | |
1983 | } | |
1984 | if (umin_ptr < umax_val) { | |
1985 | /* Overflow possible, we know nothing */ | |
1986 | dst_reg->umin_value = 0; | |
1987 | dst_reg->umax_value = U64_MAX; | |
1988 | } else { | |
1989 | /* Cannot overflow (as long as bounds are consistent) */ | |
1990 | dst_reg->umin_value = umin_ptr - umax_val; | |
1991 | dst_reg->umax_value = umax_ptr - umin_val; | |
1992 | } | |
f1174f77 EC |
1993 | dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off); |
1994 | dst_reg->off = ptr_reg->off; | |
de8f3a83 | 1995 | if (reg_is_pkt_pointer(ptr_reg)) { |
f1174f77 EC |
1996 | dst_reg->id = ++env->id_gen; |
1997 | /* something was added to pkt_ptr, set range to zero */ | |
b03c9f9f | 1998 | if (smin_val < 0) |
f1174f77 | 1999 | dst_reg->range = 0; |
43188702 | 2000 | } |
f1174f77 EC |
2001 | break; |
2002 | case BPF_AND: | |
2003 | case BPF_OR: | |
2004 | case BPF_XOR: | |
2005 | /* bitwise ops on pointers are troublesome, prohibit for now. | |
2006 | * (However, in principle we could allow some cases, e.g. | |
2007 | * ptr &= ~3 which would reduce min_value by 3.) | |
2008 | */ | |
2009 | if (!env->allow_ptr_leaks) | |
2010 | verbose("R%d bitwise operator %s on pointer prohibited\n", | |
2011 | dst, bpf_alu_string[opcode >> 4]); | |
2012 | return -EACCES; | |
2013 | default: | |
2014 | /* other operators (e.g. MUL,LSH) produce non-pointer results */ | |
2015 | if (!env->allow_ptr_leaks) | |
2016 | verbose("R%d pointer arithmetic with %s operator prohibited\n", | |
2017 | dst, bpf_alu_string[opcode >> 4]); | |
2018 | return -EACCES; | |
43188702 JF |
2019 | } |
2020 | ||
b03c9f9f EC |
2021 | __update_reg_bounds(dst_reg); |
2022 | __reg_deduce_bounds(dst_reg); | |
2023 | __reg_bound_offset(dst_reg); | |
43188702 JF |
2024 | return 0; |
2025 | } | |
2026 | ||
f1174f77 EC |
2027 | static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, |
2028 | struct bpf_insn *insn, | |
2029 | struct bpf_reg_state *dst_reg, | |
2030 | struct bpf_reg_state src_reg) | |
969bf05e | 2031 | { |
58e2af8b | 2032 | struct bpf_reg_state *regs = env->cur_state.regs; |
48461135 | 2033 | u8 opcode = BPF_OP(insn->code); |
f1174f77 | 2034 | bool src_known, dst_known; |
b03c9f9f EC |
2035 | s64 smin_val, smax_val; |
2036 | u64 umin_val, umax_val; | |
48461135 | 2037 | |
f1174f77 EC |
2038 | if (BPF_CLASS(insn->code) != BPF_ALU64) { |
2039 | /* 32-bit ALU ops are (32,32)->64 */ | |
2040 | coerce_reg_to_32(dst_reg); | |
2041 | coerce_reg_to_32(&src_reg); | |
9305706c | 2042 | } |
b03c9f9f EC |
2043 | smin_val = src_reg.smin_value; |
2044 | smax_val = src_reg.smax_value; | |
2045 | umin_val = src_reg.umin_value; | |
2046 | umax_val = src_reg.umax_value; | |
f1174f77 EC |
2047 | src_known = tnum_is_const(src_reg.var_off); |
2048 | dst_known = tnum_is_const(dst_reg->var_off); | |
f23cc643 | 2049 | |
48461135 JB |
2050 | switch (opcode) { |
2051 | case BPF_ADD: | |
b03c9f9f EC |
2052 | if (signed_add_overflows(dst_reg->smin_value, smin_val) || |
2053 | signed_add_overflows(dst_reg->smax_value, smax_val)) { | |
2054 | dst_reg->smin_value = S64_MIN; | |
2055 | dst_reg->smax_value = S64_MAX; | |
2056 | } else { | |
2057 | dst_reg->smin_value += smin_val; | |
2058 | dst_reg->smax_value += smax_val; | |
2059 | } | |
2060 | if (dst_reg->umin_value + umin_val < umin_val || | |
2061 | dst_reg->umax_value + umax_val < umax_val) { | |
2062 | dst_reg->umin_value = 0; | |
2063 | dst_reg->umax_value = U64_MAX; | |
2064 | } else { | |
2065 | dst_reg->umin_value += umin_val; | |
2066 | dst_reg->umax_value += umax_val; | |
2067 | } | |
f1174f77 | 2068 | dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off); |
48461135 JB |
2069 | break; |
2070 | case BPF_SUB: | |
b03c9f9f EC |
2071 | if (signed_sub_overflows(dst_reg->smin_value, smax_val) || |
2072 | signed_sub_overflows(dst_reg->smax_value, smin_val)) { | |
2073 | /* Overflow possible, we know nothing */ | |
2074 | dst_reg->smin_value = S64_MIN; | |
2075 | dst_reg->smax_value = S64_MAX; | |
2076 | } else { | |
2077 | dst_reg->smin_value -= smax_val; | |
2078 | dst_reg->smax_value -= smin_val; | |
2079 | } | |
2080 | if (dst_reg->umin_value < umax_val) { | |
2081 | /* Overflow possible, we know nothing */ | |
2082 | dst_reg->umin_value = 0; | |
2083 | dst_reg->umax_value = U64_MAX; | |
2084 | } else { | |
2085 | /* Cannot overflow (as long as bounds are consistent) */ | |
2086 | dst_reg->umin_value -= umax_val; | |
2087 | dst_reg->umax_value -= umin_val; | |
2088 | } | |
f1174f77 | 2089 | dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off); |
48461135 JB |
2090 | break; |
2091 | case BPF_MUL: | |
b03c9f9f EC |
2092 | dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off); |
2093 | if (smin_val < 0 || dst_reg->smin_value < 0) { | |
f1174f77 | 2094 | /* Ain't nobody got time to multiply that sign */ |
b03c9f9f EC |
2095 | __mark_reg_unbounded(dst_reg); |
2096 | __update_reg_bounds(dst_reg); | |
f1174f77 EC |
2097 | break; |
2098 | } | |
b03c9f9f EC |
2099 | /* Both values are positive, so we can work with unsigned and |
2100 | * copy the result to signed (unless it exceeds S64_MAX). | |
f1174f77 | 2101 | */ |
b03c9f9f EC |
2102 | if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) { |
2103 | /* Potential overflow, we know nothing */ | |
2104 | __mark_reg_unbounded(dst_reg); | |
2105 | /* (except what we can learn from the var_off) */ | |
2106 | __update_reg_bounds(dst_reg); | |
2107 | break; | |
2108 | } | |
2109 | dst_reg->umin_value *= umin_val; | |
2110 | dst_reg->umax_value *= umax_val; | |
2111 | if (dst_reg->umax_value > S64_MAX) { | |
2112 | /* Overflow possible, we know nothing */ | |
2113 | dst_reg->smin_value = S64_MIN; | |
2114 | dst_reg->smax_value = S64_MAX; | |
2115 | } else { | |
2116 | dst_reg->smin_value = dst_reg->umin_value; | |
2117 | dst_reg->smax_value = dst_reg->umax_value; | |
2118 | } | |
48461135 JB |
2119 | break; |
2120 | case BPF_AND: | |
f1174f77 | 2121 | if (src_known && dst_known) { |
b03c9f9f EC |
2122 | __mark_reg_known(dst_reg, dst_reg->var_off.value & |
2123 | src_reg.var_off.value); | |
f1174f77 EC |
2124 | break; |
2125 | } | |
b03c9f9f EC |
2126 | /* We get our minimum from the var_off, since that's inherently |
2127 | * bitwise. Our maximum is the minimum of the operands' maxima. | |
f23cc643 | 2128 | */ |
f1174f77 | 2129 | dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off); |
b03c9f9f EC |
2130 | dst_reg->umin_value = dst_reg->var_off.value; |
2131 | dst_reg->umax_value = min(dst_reg->umax_value, umax_val); | |
2132 | if (dst_reg->smin_value < 0 || smin_val < 0) { | |
2133 | /* Lose signed bounds when ANDing negative numbers, | |
2134 | * ain't nobody got time for that. | |
2135 | */ | |
2136 | dst_reg->smin_value = S64_MIN; | |
2137 | dst_reg->smax_value = S64_MAX; | |
2138 | } else { | |
2139 | /* ANDing two positives gives a positive, so safe to | |
2140 | * cast result into s64. | |
2141 | */ | |
2142 | dst_reg->smin_value = dst_reg->umin_value; | |
2143 | dst_reg->smax_value = dst_reg->umax_value; | |
2144 | } | |
2145 | /* We may learn something more from the var_off */ | |
2146 | __update_reg_bounds(dst_reg); | |
f1174f77 EC |
2147 | break; |
2148 | case BPF_OR: | |
2149 | if (src_known && dst_known) { | |
b03c9f9f EC |
2150 | __mark_reg_known(dst_reg, dst_reg->var_off.value | |
2151 | src_reg.var_off.value); | |
f1174f77 EC |
2152 | break; |
2153 | } | |
b03c9f9f EC |
2154 | /* We get our maximum from the var_off, and our minimum is the |
2155 | * maximum of the operands' minima | |
f1174f77 EC |
2156 | */ |
2157 | dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off); | |
b03c9f9f EC |
2158 | dst_reg->umin_value = max(dst_reg->umin_value, umin_val); |
2159 | dst_reg->umax_value = dst_reg->var_off.value | | |
2160 | dst_reg->var_off.mask; | |
2161 | if (dst_reg->smin_value < 0 || smin_val < 0) { | |
2162 | /* Lose signed bounds when ORing negative numbers, | |
2163 | * ain't nobody got time for that. | |
2164 | */ | |
2165 | dst_reg->smin_value = S64_MIN; | |
2166 | dst_reg->smax_value = S64_MAX; | |
f1174f77 | 2167 | } else { |
b03c9f9f EC |
2168 | /* ORing two positives gives a positive, so safe to |
2169 | * cast result into s64. | |
2170 | */ | |
2171 | dst_reg->smin_value = dst_reg->umin_value; | |
2172 | dst_reg->smax_value = dst_reg->umax_value; | |
f1174f77 | 2173 | } |
b03c9f9f EC |
2174 | /* We may learn something more from the var_off */ |
2175 | __update_reg_bounds(dst_reg); | |
48461135 JB |
2176 | break; |
2177 | case BPF_LSH: | |
b03c9f9f EC |
2178 | if (umax_val > 63) { |
2179 | /* Shifts greater than 63 are undefined. This includes | |
2180 | * shifts by a negative number. | |
2181 | */ | |
f1174f77 EC |
2182 | mark_reg_unknown(regs, insn->dst_reg); |
2183 | break; | |
2184 | } | |
b03c9f9f EC |
2185 | /* We lose all sign bit information (except what we can pick |
2186 | * up from var_off) | |
48461135 | 2187 | */ |
b03c9f9f EC |
2188 | dst_reg->smin_value = S64_MIN; |
2189 | dst_reg->smax_value = S64_MAX; | |
2190 | /* If we might shift our top bit out, then we know nothing */ | |
2191 | if (dst_reg->umax_value > 1ULL << (63 - umax_val)) { | |
2192 | dst_reg->umin_value = 0; | |
2193 | dst_reg->umax_value = U64_MAX; | |
d1174416 | 2194 | } else { |
b03c9f9f EC |
2195 | dst_reg->umin_value <<= umin_val; |
2196 | dst_reg->umax_value <<= umax_val; | |
d1174416 | 2197 | } |
b03c9f9f EC |
2198 | if (src_known) |
2199 | dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val); | |
2200 | else | |
2201 | dst_reg->var_off = tnum_lshift(tnum_unknown, umin_val); | |
2202 | /* We may learn something more from the var_off */ | |
2203 | __update_reg_bounds(dst_reg); | |
48461135 JB |
2204 | break; |
2205 | case BPF_RSH: | |
b03c9f9f EC |
2206 | if (umax_val > 63) { |
2207 | /* Shifts greater than 63 are undefined. This includes | |
2208 | * shifts by a negative number. | |
2209 | */ | |
f1174f77 EC |
2210 | mark_reg_unknown(regs, insn->dst_reg); |
2211 | break; | |
2212 | } | |
2213 | /* BPF_RSH is an unsigned shift, so make the appropriate casts */ | |
b03c9f9f EC |
2214 | if (dst_reg->smin_value < 0) { |
2215 | if (umin_val) { | |
f1174f77 | 2216 | /* Sign bit will be cleared */ |
b03c9f9f EC |
2217 | dst_reg->smin_value = 0; |
2218 | } else { | |
2219 | /* Lost sign bit information */ | |
2220 | dst_reg->smin_value = S64_MIN; | |
2221 | dst_reg->smax_value = S64_MAX; | |
2222 | } | |
d1174416 | 2223 | } else { |
b03c9f9f EC |
2224 | dst_reg->smin_value = |
2225 | (u64)(dst_reg->smin_value) >> umax_val; | |
d1174416 | 2226 | } |
f1174f77 | 2227 | if (src_known) |
b03c9f9f EC |
2228 | dst_reg->var_off = tnum_rshift(dst_reg->var_off, |
2229 | umin_val); | |
f1174f77 | 2230 | else |
b03c9f9f EC |
2231 | dst_reg->var_off = tnum_rshift(tnum_unknown, umin_val); |
2232 | dst_reg->umin_value >>= umax_val; | |
2233 | dst_reg->umax_value >>= umin_val; | |
2234 | /* We may learn something more from the var_off */ | |
2235 | __update_reg_bounds(dst_reg); | |
48461135 JB |
2236 | break; |
2237 | default: | |
f1174f77 | 2238 | mark_reg_unknown(regs, insn->dst_reg); |
48461135 JB |
2239 | break; |
2240 | } | |
2241 | ||
b03c9f9f EC |
2242 | __reg_deduce_bounds(dst_reg); |
2243 | __reg_bound_offset(dst_reg); | |
f1174f77 EC |
2244 | return 0; |
2245 | } | |
2246 | ||
2247 | /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max | |
2248 | * and var_off. | |
2249 | */ | |
2250 | static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, | |
2251 | struct bpf_insn *insn) | |
2252 | { | |
2253 | struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg, *src_reg; | |
2254 | struct bpf_reg_state *ptr_reg = NULL, off_reg = {0}; | |
2255 | u8 opcode = BPF_OP(insn->code); | |
2256 | int rc; | |
2257 | ||
2258 | dst_reg = ®s[insn->dst_reg]; | |
f1174f77 EC |
2259 | src_reg = NULL; |
2260 | if (dst_reg->type != SCALAR_VALUE) | |
2261 | ptr_reg = dst_reg; | |
2262 | if (BPF_SRC(insn->code) == BPF_X) { | |
2263 | src_reg = ®s[insn->src_reg]; | |
f1174f77 EC |
2264 | if (src_reg->type != SCALAR_VALUE) { |
2265 | if (dst_reg->type != SCALAR_VALUE) { | |
2266 | /* Combining two pointers by any ALU op yields | |
2267 | * an arbitrary scalar. | |
2268 | */ | |
2269 | if (!env->allow_ptr_leaks) { | |
2270 | verbose("R%d pointer %s pointer prohibited\n", | |
2271 | insn->dst_reg, | |
2272 | bpf_alu_string[opcode >> 4]); | |
2273 | return -EACCES; | |
2274 | } | |
2275 | mark_reg_unknown(regs, insn->dst_reg); | |
2276 | return 0; | |
2277 | } else { | |
2278 | /* scalar += pointer | |
2279 | * This is legal, but we have to reverse our | |
2280 | * src/dest handling in computing the range | |
2281 | */ | |
2282 | rc = adjust_ptr_min_max_vals(env, insn, | |
2283 | src_reg, dst_reg); | |
2284 | if (rc == -EACCES && env->allow_ptr_leaks) { | |
2285 | /* scalar += unknown scalar */ | |
2286 | __mark_reg_unknown(&off_reg); | |
2287 | return adjust_scalar_min_max_vals( | |
2288 | env, insn, | |
2289 | dst_reg, off_reg); | |
2290 | } | |
2291 | return rc; | |
2292 | } | |
2293 | } else if (ptr_reg) { | |
2294 | /* pointer += scalar */ | |
2295 | rc = adjust_ptr_min_max_vals(env, insn, | |
2296 | dst_reg, src_reg); | |
2297 | if (rc == -EACCES && env->allow_ptr_leaks) { | |
2298 | /* unknown scalar += scalar */ | |
2299 | __mark_reg_unknown(dst_reg); | |
2300 | return adjust_scalar_min_max_vals( | |
2301 | env, insn, dst_reg, *src_reg); | |
2302 | } | |
2303 | return rc; | |
2304 | } | |
2305 | } else { | |
2306 | /* Pretend the src is a reg with a known value, since we only | |
2307 | * need to be able to read from this state. | |
2308 | */ | |
2309 | off_reg.type = SCALAR_VALUE; | |
b03c9f9f | 2310 | __mark_reg_known(&off_reg, insn->imm); |
f1174f77 | 2311 | src_reg = &off_reg; |
f1174f77 EC |
2312 | if (ptr_reg) { /* pointer += K */ |
2313 | rc = adjust_ptr_min_max_vals(env, insn, | |
2314 | ptr_reg, src_reg); | |
2315 | if (rc == -EACCES && env->allow_ptr_leaks) { | |
2316 | /* unknown scalar += K */ | |
2317 | __mark_reg_unknown(dst_reg); | |
2318 | return adjust_scalar_min_max_vals( | |
2319 | env, insn, dst_reg, off_reg); | |
2320 | } | |
2321 | return rc; | |
2322 | } | |
2323 | } | |
2324 | ||
2325 | /* Got here implies adding two SCALAR_VALUEs */ | |
2326 | if (WARN_ON_ONCE(ptr_reg)) { | |
2327 | print_verifier_state(&env->cur_state); | |
2328 | verbose("verifier internal error: unexpected ptr_reg\n"); | |
2329 | return -EINVAL; | |
2330 | } | |
2331 | if (WARN_ON(!src_reg)) { | |
2332 | print_verifier_state(&env->cur_state); | |
2333 | verbose("verifier internal error: no src_reg\n"); | |
2334 | return -EINVAL; | |
2335 | } | |
2336 | return adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg); | |
48461135 JB |
2337 | } |
2338 | ||
17a52670 | 2339 | /* check validity of 32-bit and 64-bit arithmetic operations */ |
58e2af8b | 2340 | static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 2341 | { |
f1174f77 | 2342 | struct bpf_reg_state *regs = env->cur_state.regs; |
17a52670 AS |
2343 | u8 opcode = BPF_OP(insn->code); |
2344 | int err; | |
2345 | ||
2346 | if (opcode == BPF_END || opcode == BPF_NEG) { | |
2347 | if (opcode == BPF_NEG) { | |
2348 | if (BPF_SRC(insn->code) != 0 || | |
2349 | insn->src_reg != BPF_REG_0 || | |
2350 | insn->off != 0 || insn->imm != 0) { | |
2351 | verbose("BPF_NEG uses reserved fields\n"); | |
2352 | return -EINVAL; | |
2353 | } | |
2354 | } else { | |
2355 | if (insn->src_reg != BPF_REG_0 || insn->off != 0 || | |
e67b8a68 EC |
2356 | (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) || |
2357 | BPF_CLASS(insn->code) == BPF_ALU64) { | |
17a52670 AS |
2358 | verbose("BPF_END uses reserved fields\n"); |
2359 | return -EINVAL; | |
2360 | } | |
2361 | } | |
2362 | ||
2363 | /* check src operand */ | |
dc503a8a | 2364 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
2365 | if (err) |
2366 | return err; | |
2367 | ||
1be7f75d AS |
2368 | if (is_pointer_value(env, insn->dst_reg)) { |
2369 | verbose("R%d pointer arithmetic prohibited\n", | |
2370 | insn->dst_reg); | |
2371 | return -EACCES; | |
2372 | } | |
2373 | ||
17a52670 | 2374 | /* check dest operand */ |
dc503a8a | 2375 | err = check_reg_arg(env, insn->dst_reg, DST_OP); |
17a52670 AS |
2376 | if (err) |
2377 | return err; | |
2378 | ||
2379 | } else if (opcode == BPF_MOV) { | |
2380 | ||
2381 | if (BPF_SRC(insn->code) == BPF_X) { | |
2382 | if (insn->imm != 0 || insn->off != 0) { | |
2383 | verbose("BPF_MOV uses reserved fields\n"); | |
2384 | return -EINVAL; | |
2385 | } | |
2386 | ||
2387 | /* check src operand */ | |
dc503a8a | 2388 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
2389 | if (err) |
2390 | return err; | |
2391 | } else { | |
2392 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
2393 | verbose("BPF_MOV uses reserved fields\n"); | |
2394 | return -EINVAL; | |
2395 | } | |
2396 | } | |
2397 | ||
2398 | /* check dest operand */ | |
dc503a8a | 2399 | err = check_reg_arg(env, insn->dst_reg, DST_OP); |
17a52670 AS |
2400 | if (err) |
2401 | return err; | |
2402 | ||
2403 | if (BPF_SRC(insn->code) == BPF_X) { | |
2404 | if (BPF_CLASS(insn->code) == BPF_ALU64) { | |
2405 | /* case: R1 = R2 | |
2406 | * copy register state to dest reg | |
2407 | */ | |
2408 | regs[insn->dst_reg] = regs[insn->src_reg]; | |
8fe2d6cc | 2409 | regs[insn->dst_reg].live |= REG_LIVE_WRITTEN; |
17a52670 | 2410 | } else { |
f1174f77 | 2411 | /* R1 = (u32) R2 */ |
1be7f75d AS |
2412 | if (is_pointer_value(env, insn->src_reg)) { |
2413 | verbose("R%d partial copy of pointer\n", | |
2414 | insn->src_reg); | |
2415 | return -EACCES; | |
2416 | } | |
f1174f77 | 2417 | mark_reg_unknown(regs, insn->dst_reg); |
b03c9f9f | 2418 | /* high 32 bits are known zero. */ |
f1174f77 EC |
2419 | regs[insn->dst_reg].var_off = tnum_cast( |
2420 | regs[insn->dst_reg].var_off, 4); | |
b03c9f9f | 2421 | __update_reg_bounds(®s[insn->dst_reg]); |
17a52670 AS |
2422 | } |
2423 | } else { | |
2424 | /* case: R = imm | |
2425 | * remember the value we stored into this reg | |
2426 | */ | |
f1174f77 | 2427 | regs[insn->dst_reg].type = SCALAR_VALUE; |
b03c9f9f | 2428 | __mark_reg_known(regs + insn->dst_reg, insn->imm); |
17a52670 AS |
2429 | } |
2430 | ||
2431 | } else if (opcode > BPF_END) { | |
2432 | verbose("invalid BPF_ALU opcode %x\n", opcode); | |
2433 | return -EINVAL; | |
2434 | ||
2435 | } else { /* all other ALU ops: and, sub, xor, add, ... */ | |
2436 | ||
17a52670 AS |
2437 | if (BPF_SRC(insn->code) == BPF_X) { |
2438 | if (insn->imm != 0 || insn->off != 0) { | |
2439 | verbose("BPF_ALU uses reserved fields\n"); | |
2440 | return -EINVAL; | |
2441 | } | |
2442 | /* check src1 operand */ | |
dc503a8a | 2443 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
2444 | if (err) |
2445 | return err; | |
2446 | } else { | |
2447 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
2448 | verbose("BPF_ALU uses reserved fields\n"); | |
2449 | return -EINVAL; | |
2450 | } | |
2451 | } | |
2452 | ||
2453 | /* check src2 operand */ | |
dc503a8a | 2454 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
2455 | if (err) |
2456 | return err; | |
2457 | ||
2458 | if ((opcode == BPF_MOD || opcode == BPF_DIV) && | |
2459 | BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { | |
2460 | verbose("div by zero\n"); | |
2461 | return -EINVAL; | |
2462 | } | |
2463 | ||
229394e8 RV |
2464 | if ((opcode == BPF_LSH || opcode == BPF_RSH || |
2465 | opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { | |
2466 | int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; | |
2467 | ||
2468 | if (insn->imm < 0 || insn->imm >= size) { | |
2469 | verbose("invalid shift %d\n", insn->imm); | |
2470 | return -EINVAL; | |
2471 | } | |
2472 | } | |
2473 | ||
1a0dc1ac | 2474 | /* check dest operand */ |
dc503a8a | 2475 | err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); |
1a0dc1ac AS |
2476 | if (err) |
2477 | return err; | |
2478 | ||
f1174f77 | 2479 | return adjust_reg_min_max_vals(env, insn); |
17a52670 AS |
2480 | } |
2481 | ||
2482 | return 0; | |
2483 | } | |
2484 | ||
58e2af8b | 2485 | static void find_good_pkt_pointers(struct bpf_verifier_state *state, |
de8f3a83 DB |
2486 | struct bpf_reg_state *dst_reg, |
2487 | enum bpf_reg_type type) | |
969bf05e | 2488 | { |
58e2af8b | 2489 | struct bpf_reg_state *regs = state->regs, *reg; |
969bf05e | 2490 | int i; |
2d2be8ca | 2491 | |
f1174f77 EC |
2492 | if (dst_reg->off < 0) |
2493 | /* This doesn't give us any range */ | |
2494 | return; | |
2495 | ||
b03c9f9f EC |
2496 | if (dst_reg->umax_value > MAX_PACKET_OFF || |
2497 | dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF) | |
f1174f77 EC |
2498 | /* Risk of overflow. For instance, ptr + (1<<63) may be less |
2499 | * than pkt_end, but that's because it's also less than pkt. | |
2500 | */ | |
2501 | return; | |
2502 | ||
b4e432f1 | 2503 | /* LLVM can generate four kind of checks: |
2d2be8ca | 2504 | * |
b4e432f1 | 2505 | * Type 1/2: |
2d2be8ca DB |
2506 | * |
2507 | * r2 = r3; | |
2508 | * r2 += 8; | |
2509 | * if (r2 > pkt_end) goto <handle exception> | |
2510 | * <access okay> | |
2511 | * | |
b4e432f1 DB |
2512 | * r2 = r3; |
2513 | * r2 += 8; | |
2514 | * if (r2 < pkt_end) goto <access okay> | |
2515 | * <handle exception> | |
2516 | * | |
2d2be8ca DB |
2517 | * Where: |
2518 | * r2 == dst_reg, pkt_end == src_reg | |
2519 | * r2=pkt(id=n,off=8,r=0) | |
2520 | * r3=pkt(id=n,off=0,r=0) | |
2521 | * | |
b4e432f1 | 2522 | * Type 3/4: |
2d2be8ca DB |
2523 | * |
2524 | * r2 = r3; | |
2525 | * r2 += 8; | |
2526 | * if (pkt_end >= r2) goto <access okay> | |
2527 | * <handle exception> | |
2528 | * | |
b4e432f1 DB |
2529 | * r2 = r3; |
2530 | * r2 += 8; | |
2531 | * if (pkt_end <= r2) goto <handle exception> | |
2532 | * <access okay> | |
2533 | * | |
2d2be8ca DB |
2534 | * Where: |
2535 | * pkt_end == dst_reg, r2 == src_reg | |
2536 | * r2=pkt(id=n,off=8,r=0) | |
2537 | * r3=pkt(id=n,off=0,r=0) | |
2538 | * | |
2539 | * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) | |
2540 | * so that range of bytes [r3, r3 + 8) is safe to access. | |
969bf05e | 2541 | */ |
2d2be8ca | 2542 | |
f1174f77 EC |
2543 | /* If our ids match, then we must have the same max_value. And we |
2544 | * don't care about the other reg's fixed offset, since if it's too big | |
2545 | * the range won't allow anything. | |
2546 | * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16. | |
2547 | */ | |
969bf05e | 2548 | for (i = 0; i < MAX_BPF_REG; i++) |
de8f3a83 | 2549 | if (regs[i].type == type && regs[i].id == dst_reg->id) |
b1977682 | 2550 | /* keep the maximum range already checked */ |
f1174f77 | 2551 | regs[i].range = max_t(u16, regs[i].range, dst_reg->off); |
969bf05e AS |
2552 | |
2553 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
2554 | if (state->stack_slot_type[i] != STACK_SPILL) | |
2555 | continue; | |
2556 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
de8f3a83 | 2557 | if (reg->type == type && reg->id == dst_reg->id) |
f1174f77 | 2558 | reg->range = max_t(u16, reg->range, dst_reg->off); |
969bf05e AS |
2559 | } |
2560 | } | |
2561 | ||
48461135 JB |
2562 | /* Adjusts the register min/max values in the case that the dst_reg is the |
2563 | * variable register that we are working on, and src_reg is a constant or we're | |
2564 | * simply doing a BPF_K check. | |
f1174f77 | 2565 | * In JEQ/JNE cases we also adjust the var_off values. |
48461135 JB |
2566 | */ |
2567 | static void reg_set_min_max(struct bpf_reg_state *true_reg, | |
2568 | struct bpf_reg_state *false_reg, u64 val, | |
2569 | u8 opcode) | |
2570 | { | |
f1174f77 EC |
2571 | /* If the dst_reg is a pointer, we can't learn anything about its |
2572 | * variable offset from the compare (unless src_reg were a pointer into | |
2573 | * the same object, but we don't bother with that. | |
2574 | * Since false_reg and true_reg have the same type by construction, we | |
2575 | * only need to check one of them for pointerness. | |
2576 | */ | |
2577 | if (__is_pointer_value(false, false_reg)) | |
2578 | return; | |
4cabc5b1 | 2579 | |
48461135 JB |
2580 | switch (opcode) { |
2581 | case BPF_JEQ: | |
2582 | /* If this is false then we know nothing Jon Snow, but if it is | |
2583 | * true then we know for sure. | |
2584 | */ | |
b03c9f9f | 2585 | __mark_reg_known(true_reg, val); |
48461135 JB |
2586 | break; |
2587 | case BPF_JNE: | |
2588 | /* If this is true we know nothing Jon Snow, but if it is false | |
2589 | * we know the value for sure; | |
2590 | */ | |
b03c9f9f | 2591 | __mark_reg_known(false_reg, val); |
48461135 JB |
2592 | break; |
2593 | case BPF_JGT: | |
b03c9f9f EC |
2594 | false_reg->umax_value = min(false_reg->umax_value, val); |
2595 | true_reg->umin_value = max(true_reg->umin_value, val + 1); | |
2596 | break; | |
48461135 | 2597 | case BPF_JSGT: |
b03c9f9f EC |
2598 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val); |
2599 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1); | |
48461135 | 2600 | break; |
b4e432f1 DB |
2601 | case BPF_JLT: |
2602 | false_reg->umin_value = max(false_reg->umin_value, val); | |
2603 | true_reg->umax_value = min(true_reg->umax_value, val - 1); | |
2604 | break; | |
2605 | case BPF_JSLT: | |
2606 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val); | |
2607 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1); | |
2608 | break; | |
48461135 | 2609 | case BPF_JGE: |
b03c9f9f EC |
2610 | false_reg->umax_value = min(false_reg->umax_value, val - 1); |
2611 | true_reg->umin_value = max(true_reg->umin_value, val); | |
2612 | break; | |
48461135 | 2613 | case BPF_JSGE: |
b03c9f9f EC |
2614 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1); |
2615 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val); | |
48461135 | 2616 | break; |
b4e432f1 DB |
2617 | case BPF_JLE: |
2618 | false_reg->umin_value = max(false_reg->umin_value, val + 1); | |
2619 | true_reg->umax_value = min(true_reg->umax_value, val); | |
2620 | break; | |
2621 | case BPF_JSLE: | |
2622 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1); | |
2623 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val); | |
2624 | break; | |
48461135 JB |
2625 | default: |
2626 | break; | |
2627 | } | |
2628 | ||
b03c9f9f EC |
2629 | __reg_deduce_bounds(false_reg); |
2630 | __reg_deduce_bounds(true_reg); | |
2631 | /* We might have learned some bits from the bounds. */ | |
2632 | __reg_bound_offset(false_reg); | |
2633 | __reg_bound_offset(true_reg); | |
2634 | /* Intersecting with the old var_off might have improved our bounds | |
2635 | * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), | |
2636 | * then new var_off is (0; 0x7f...fc) which improves our umax. | |
2637 | */ | |
2638 | __update_reg_bounds(false_reg); | |
2639 | __update_reg_bounds(true_reg); | |
48461135 JB |
2640 | } |
2641 | ||
f1174f77 EC |
2642 | /* Same as above, but for the case that dst_reg holds a constant and src_reg is |
2643 | * the variable reg. | |
48461135 JB |
2644 | */ |
2645 | static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, | |
2646 | struct bpf_reg_state *false_reg, u64 val, | |
2647 | u8 opcode) | |
2648 | { | |
f1174f77 EC |
2649 | if (__is_pointer_value(false, false_reg)) |
2650 | return; | |
4cabc5b1 | 2651 | |
48461135 JB |
2652 | switch (opcode) { |
2653 | case BPF_JEQ: | |
2654 | /* If this is false then we know nothing Jon Snow, but if it is | |
2655 | * true then we know for sure. | |
2656 | */ | |
b03c9f9f | 2657 | __mark_reg_known(true_reg, val); |
48461135 JB |
2658 | break; |
2659 | case BPF_JNE: | |
2660 | /* If this is true we know nothing Jon Snow, but if it is false | |
2661 | * we know the value for sure; | |
2662 | */ | |
b03c9f9f | 2663 | __mark_reg_known(false_reg, val); |
48461135 JB |
2664 | break; |
2665 | case BPF_JGT: | |
b03c9f9f EC |
2666 | true_reg->umax_value = min(true_reg->umax_value, val - 1); |
2667 | false_reg->umin_value = max(false_reg->umin_value, val); | |
2668 | break; | |
48461135 | 2669 | case BPF_JSGT: |
b03c9f9f EC |
2670 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1); |
2671 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val); | |
48461135 | 2672 | break; |
b4e432f1 DB |
2673 | case BPF_JLT: |
2674 | true_reg->umin_value = max(true_reg->umin_value, val + 1); | |
2675 | false_reg->umax_value = min(false_reg->umax_value, val); | |
2676 | break; | |
2677 | case BPF_JSLT: | |
2678 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1); | |
2679 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val); | |
2680 | break; | |
48461135 | 2681 | case BPF_JGE: |
b03c9f9f EC |
2682 | true_reg->umax_value = min(true_reg->umax_value, val); |
2683 | false_reg->umin_value = max(false_reg->umin_value, val + 1); | |
2684 | break; | |
48461135 | 2685 | case BPF_JSGE: |
b03c9f9f EC |
2686 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val); |
2687 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1); | |
48461135 | 2688 | break; |
b4e432f1 DB |
2689 | case BPF_JLE: |
2690 | true_reg->umin_value = max(true_reg->umin_value, val); | |
2691 | false_reg->umax_value = min(false_reg->umax_value, val - 1); | |
2692 | break; | |
2693 | case BPF_JSLE: | |
2694 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val); | |
2695 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1); | |
2696 | break; | |
48461135 JB |
2697 | default: |
2698 | break; | |
2699 | } | |
2700 | ||
b03c9f9f EC |
2701 | __reg_deduce_bounds(false_reg); |
2702 | __reg_deduce_bounds(true_reg); | |
2703 | /* We might have learned some bits from the bounds. */ | |
2704 | __reg_bound_offset(false_reg); | |
2705 | __reg_bound_offset(true_reg); | |
2706 | /* Intersecting with the old var_off might have improved our bounds | |
2707 | * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), | |
2708 | * then new var_off is (0; 0x7f...fc) which improves our umax. | |
2709 | */ | |
2710 | __update_reg_bounds(false_reg); | |
2711 | __update_reg_bounds(true_reg); | |
f1174f77 EC |
2712 | } |
2713 | ||
2714 | /* Regs are known to be equal, so intersect their min/max/var_off */ | |
2715 | static void __reg_combine_min_max(struct bpf_reg_state *src_reg, | |
2716 | struct bpf_reg_state *dst_reg) | |
2717 | { | |
b03c9f9f EC |
2718 | src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value, |
2719 | dst_reg->umin_value); | |
2720 | src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value, | |
2721 | dst_reg->umax_value); | |
2722 | src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value, | |
2723 | dst_reg->smin_value); | |
2724 | src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value, | |
2725 | dst_reg->smax_value); | |
f1174f77 EC |
2726 | src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off, |
2727 | dst_reg->var_off); | |
b03c9f9f EC |
2728 | /* We might have learned new bounds from the var_off. */ |
2729 | __update_reg_bounds(src_reg); | |
2730 | __update_reg_bounds(dst_reg); | |
2731 | /* We might have learned something about the sign bit. */ | |
2732 | __reg_deduce_bounds(src_reg); | |
2733 | __reg_deduce_bounds(dst_reg); | |
2734 | /* We might have learned some bits from the bounds. */ | |
2735 | __reg_bound_offset(src_reg); | |
2736 | __reg_bound_offset(dst_reg); | |
2737 | /* Intersecting with the old var_off might have improved our bounds | |
2738 | * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), | |
2739 | * then new var_off is (0; 0x7f...fc) which improves our umax. | |
2740 | */ | |
2741 | __update_reg_bounds(src_reg); | |
2742 | __update_reg_bounds(dst_reg); | |
f1174f77 EC |
2743 | } |
2744 | ||
2745 | static void reg_combine_min_max(struct bpf_reg_state *true_src, | |
2746 | struct bpf_reg_state *true_dst, | |
2747 | struct bpf_reg_state *false_src, | |
2748 | struct bpf_reg_state *false_dst, | |
2749 | u8 opcode) | |
2750 | { | |
2751 | switch (opcode) { | |
2752 | case BPF_JEQ: | |
2753 | __reg_combine_min_max(true_src, true_dst); | |
2754 | break; | |
2755 | case BPF_JNE: | |
2756 | __reg_combine_min_max(false_src, false_dst); | |
b03c9f9f | 2757 | break; |
4cabc5b1 | 2758 | } |
48461135 JB |
2759 | } |
2760 | ||
57a09bf0 | 2761 | static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id, |
f1174f77 | 2762 | bool is_null) |
57a09bf0 TG |
2763 | { |
2764 | struct bpf_reg_state *reg = ®s[regno]; | |
2765 | ||
2766 | if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) { | |
f1174f77 EC |
2767 | /* Old offset (both fixed and variable parts) should |
2768 | * have been known-zero, because we don't allow pointer | |
2769 | * arithmetic on pointers that might be NULL. | |
2770 | */ | |
b03c9f9f EC |
2771 | if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || |
2772 | !tnum_equals_const(reg->var_off, 0) || | |
f1174f77 | 2773 | reg->off)) { |
b03c9f9f EC |
2774 | __mark_reg_known_zero(reg); |
2775 | reg->off = 0; | |
f1174f77 EC |
2776 | } |
2777 | if (is_null) { | |
2778 | reg->type = SCALAR_VALUE; | |
56f668df MKL |
2779 | } else if (reg->map_ptr->inner_map_meta) { |
2780 | reg->type = CONST_PTR_TO_MAP; | |
2781 | reg->map_ptr = reg->map_ptr->inner_map_meta; | |
2782 | } else { | |
f1174f77 | 2783 | reg->type = PTR_TO_MAP_VALUE; |
56f668df | 2784 | } |
a08dd0da DB |
2785 | /* We don't need id from this point onwards anymore, thus we |
2786 | * should better reset it, so that state pruning has chances | |
2787 | * to take effect. | |
2788 | */ | |
2789 | reg->id = 0; | |
57a09bf0 TG |
2790 | } |
2791 | } | |
2792 | ||
2793 | /* The logic is similar to find_good_pkt_pointers(), both could eventually | |
2794 | * be folded together at some point. | |
2795 | */ | |
2796 | static void mark_map_regs(struct bpf_verifier_state *state, u32 regno, | |
f1174f77 | 2797 | bool is_null) |
57a09bf0 TG |
2798 | { |
2799 | struct bpf_reg_state *regs = state->regs; | |
a08dd0da | 2800 | u32 id = regs[regno].id; |
57a09bf0 TG |
2801 | int i; |
2802 | ||
2803 | for (i = 0; i < MAX_BPF_REG; i++) | |
f1174f77 | 2804 | mark_map_reg(regs, i, id, is_null); |
57a09bf0 TG |
2805 | |
2806 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
2807 | if (state->stack_slot_type[i] != STACK_SPILL) | |
2808 | continue; | |
f1174f77 | 2809 | mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, is_null); |
57a09bf0 TG |
2810 | } |
2811 | } | |
2812 | ||
58e2af8b | 2813 | static int check_cond_jmp_op(struct bpf_verifier_env *env, |
17a52670 AS |
2814 | struct bpf_insn *insn, int *insn_idx) |
2815 | { | |
58e2af8b JK |
2816 | struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state; |
2817 | struct bpf_reg_state *regs = this_branch->regs, *dst_reg; | |
17a52670 AS |
2818 | u8 opcode = BPF_OP(insn->code); |
2819 | int err; | |
2820 | ||
b4e432f1 | 2821 | if (opcode > BPF_JSLE) { |
17a52670 AS |
2822 | verbose("invalid BPF_JMP opcode %x\n", opcode); |
2823 | return -EINVAL; | |
2824 | } | |
2825 | ||
2826 | if (BPF_SRC(insn->code) == BPF_X) { | |
2827 | if (insn->imm != 0) { | |
2828 | verbose("BPF_JMP uses reserved fields\n"); | |
2829 | return -EINVAL; | |
2830 | } | |
2831 | ||
2832 | /* check src1 operand */ | |
dc503a8a | 2833 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
2834 | if (err) |
2835 | return err; | |
1be7f75d AS |
2836 | |
2837 | if (is_pointer_value(env, insn->src_reg)) { | |
2838 | verbose("R%d pointer comparison prohibited\n", | |
2839 | insn->src_reg); | |
2840 | return -EACCES; | |
2841 | } | |
17a52670 AS |
2842 | } else { |
2843 | if (insn->src_reg != BPF_REG_0) { | |
2844 | verbose("BPF_JMP uses reserved fields\n"); | |
2845 | return -EINVAL; | |
2846 | } | |
2847 | } | |
2848 | ||
2849 | /* check src2 operand */ | |
dc503a8a | 2850 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
2851 | if (err) |
2852 | return err; | |
2853 | ||
1a0dc1ac AS |
2854 | dst_reg = ®s[insn->dst_reg]; |
2855 | ||
17a52670 AS |
2856 | /* detect if R == 0 where R was initialized to zero earlier */ |
2857 | if (BPF_SRC(insn->code) == BPF_K && | |
2858 | (opcode == BPF_JEQ || opcode == BPF_JNE) && | |
f1174f77 EC |
2859 | dst_reg->type == SCALAR_VALUE && |
2860 | tnum_equals_const(dst_reg->var_off, insn->imm)) { | |
17a52670 AS |
2861 | if (opcode == BPF_JEQ) { |
2862 | /* if (imm == imm) goto pc+off; | |
2863 | * only follow the goto, ignore fall-through | |
2864 | */ | |
2865 | *insn_idx += insn->off; | |
2866 | return 0; | |
2867 | } else { | |
2868 | /* if (imm != imm) goto pc+off; | |
2869 | * only follow fall-through branch, since | |
2870 | * that's where the program will go | |
2871 | */ | |
2872 | return 0; | |
2873 | } | |
2874 | } | |
2875 | ||
2876 | other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); | |
2877 | if (!other_branch) | |
2878 | return -EFAULT; | |
2879 | ||
48461135 JB |
2880 | /* detect if we are comparing against a constant value so we can adjust |
2881 | * our min/max values for our dst register. | |
f1174f77 EC |
2882 | * this is only legit if both are scalars (or pointers to the same |
2883 | * object, I suppose, but we don't support that right now), because | |
2884 | * otherwise the different base pointers mean the offsets aren't | |
2885 | * comparable. | |
48461135 JB |
2886 | */ |
2887 | if (BPF_SRC(insn->code) == BPF_X) { | |
f1174f77 EC |
2888 | if (dst_reg->type == SCALAR_VALUE && |
2889 | regs[insn->src_reg].type == SCALAR_VALUE) { | |
2890 | if (tnum_is_const(regs[insn->src_reg].var_off)) | |
2891 | reg_set_min_max(&other_branch->regs[insn->dst_reg], | |
2892 | dst_reg, regs[insn->src_reg].var_off.value, | |
2893 | opcode); | |
2894 | else if (tnum_is_const(dst_reg->var_off)) | |
2895 | reg_set_min_max_inv(&other_branch->regs[insn->src_reg], | |
2896 | ®s[insn->src_reg], | |
2897 | dst_reg->var_off.value, opcode); | |
2898 | else if (opcode == BPF_JEQ || opcode == BPF_JNE) | |
2899 | /* Comparing for equality, we can combine knowledge */ | |
2900 | reg_combine_min_max(&other_branch->regs[insn->src_reg], | |
2901 | &other_branch->regs[insn->dst_reg], | |
2902 | ®s[insn->src_reg], | |
2903 | ®s[insn->dst_reg], opcode); | |
2904 | } | |
2905 | } else if (dst_reg->type == SCALAR_VALUE) { | |
48461135 JB |
2906 | reg_set_min_max(&other_branch->regs[insn->dst_reg], |
2907 | dst_reg, insn->imm, opcode); | |
2908 | } | |
2909 | ||
58e2af8b | 2910 | /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */ |
17a52670 | 2911 | if (BPF_SRC(insn->code) == BPF_K && |
1a0dc1ac AS |
2912 | insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && |
2913 | dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { | |
57a09bf0 TG |
2914 | /* Mark all identical map registers in each branch as either |
2915 | * safe or unknown depending R == 0 or R != 0 conditional. | |
2916 | */ | |
f1174f77 EC |
2917 | mark_map_regs(this_branch, insn->dst_reg, opcode == BPF_JNE); |
2918 | mark_map_regs(other_branch, insn->dst_reg, opcode == BPF_JEQ); | |
969bf05e AS |
2919 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && |
2920 | dst_reg->type == PTR_TO_PACKET && | |
2921 | regs[insn->src_reg].type == PTR_TO_PACKET_END) { | |
de8f3a83 | 2922 | find_good_pkt_pointers(this_branch, dst_reg, PTR_TO_PACKET); |
b4e432f1 DB |
2923 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLT && |
2924 | dst_reg->type == PTR_TO_PACKET && | |
2925 | regs[insn->src_reg].type == PTR_TO_PACKET_END) { | |
de8f3a83 | 2926 | find_good_pkt_pointers(other_branch, dst_reg, PTR_TO_PACKET); |
2d2be8ca DB |
2927 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE && |
2928 | dst_reg->type == PTR_TO_PACKET_END && | |
2929 | regs[insn->src_reg].type == PTR_TO_PACKET) { | |
de8f3a83 DB |
2930 | find_good_pkt_pointers(other_branch, ®s[insn->src_reg], |
2931 | PTR_TO_PACKET); | |
b4e432f1 DB |
2932 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLE && |
2933 | dst_reg->type == PTR_TO_PACKET_END && | |
2934 | regs[insn->src_reg].type == PTR_TO_PACKET) { | |
de8f3a83 DB |
2935 | find_good_pkt_pointers(this_branch, ®s[insn->src_reg], |
2936 | PTR_TO_PACKET); | |
2937 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && | |
2938 | dst_reg->type == PTR_TO_PACKET_META && | |
2939 | reg_is_init_pkt_pointer(®s[insn->src_reg], PTR_TO_PACKET)) { | |
2940 | find_good_pkt_pointers(this_branch, dst_reg, PTR_TO_PACKET_META); | |
2941 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLT && | |
2942 | dst_reg->type == PTR_TO_PACKET_META && | |
2943 | reg_is_init_pkt_pointer(®s[insn->src_reg], PTR_TO_PACKET)) { | |
2944 | find_good_pkt_pointers(other_branch, dst_reg, PTR_TO_PACKET_META); | |
2945 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE && | |
2946 | reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && | |
2947 | regs[insn->src_reg].type == PTR_TO_PACKET_META) { | |
2948 | find_good_pkt_pointers(other_branch, ®s[insn->src_reg], | |
2949 | PTR_TO_PACKET_META); | |
2950 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLE && | |
2951 | reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && | |
2952 | regs[insn->src_reg].type == PTR_TO_PACKET_META) { | |
2953 | find_good_pkt_pointers(this_branch, ®s[insn->src_reg], | |
2954 | PTR_TO_PACKET_META); | |
1be7f75d AS |
2955 | } else if (is_pointer_value(env, insn->dst_reg)) { |
2956 | verbose("R%d pointer comparison prohibited\n", insn->dst_reg); | |
2957 | return -EACCES; | |
17a52670 AS |
2958 | } |
2959 | if (log_level) | |
2d2be8ca | 2960 | print_verifier_state(this_branch); |
17a52670 AS |
2961 | return 0; |
2962 | } | |
2963 | ||
0246e64d AS |
2964 | /* return the map pointer stored inside BPF_LD_IMM64 instruction */ |
2965 | static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) | |
2966 | { | |
2967 | u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; | |
2968 | ||
2969 | return (struct bpf_map *) (unsigned long) imm64; | |
2970 | } | |
2971 | ||
17a52670 | 2972 | /* verify BPF_LD_IMM64 instruction */ |
58e2af8b | 2973 | static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 2974 | { |
58e2af8b | 2975 | struct bpf_reg_state *regs = env->cur_state.regs; |
17a52670 AS |
2976 | int err; |
2977 | ||
2978 | if (BPF_SIZE(insn->code) != BPF_DW) { | |
2979 | verbose("invalid BPF_LD_IMM insn\n"); | |
2980 | return -EINVAL; | |
2981 | } | |
2982 | if (insn->off != 0) { | |
2983 | verbose("BPF_LD_IMM64 uses reserved fields\n"); | |
2984 | return -EINVAL; | |
2985 | } | |
2986 | ||
dc503a8a | 2987 | err = check_reg_arg(env, insn->dst_reg, DST_OP); |
17a52670 AS |
2988 | if (err) |
2989 | return err; | |
2990 | ||
6b173873 | 2991 | if (insn->src_reg == 0) { |
6b173873 JK |
2992 | u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; |
2993 | ||
f1174f77 | 2994 | regs[insn->dst_reg].type = SCALAR_VALUE; |
b03c9f9f | 2995 | __mark_reg_known(®s[insn->dst_reg], imm); |
17a52670 | 2996 | return 0; |
6b173873 | 2997 | } |
17a52670 AS |
2998 | |
2999 | /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ | |
3000 | BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); | |
3001 | ||
3002 | regs[insn->dst_reg].type = CONST_PTR_TO_MAP; | |
3003 | regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); | |
3004 | return 0; | |
3005 | } | |
3006 | ||
96be4325 DB |
3007 | static bool may_access_skb(enum bpf_prog_type type) |
3008 | { | |
3009 | switch (type) { | |
3010 | case BPF_PROG_TYPE_SOCKET_FILTER: | |
3011 | case BPF_PROG_TYPE_SCHED_CLS: | |
94caee8c | 3012 | case BPF_PROG_TYPE_SCHED_ACT: |
96be4325 DB |
3013 | return true; |
3014 | default: | |
3015 | return false; | |
3016 | } | |
3017 | } | |
3018 | ||
ddd872bc AS |
3019 | /* verify safety of LD_ABS|LD_IND instructions: |
3020 | * - they can only appear in the programs where ctx == skb | |
3021 | * - since they are wrappers of function calls, they scratch R1-R5 registers, | |
3022 | * preserve R6-R9, and store return value into R0 | |
3023 | * | |
3024 | * Implicit input: | |
3025 | * ctx == skb == R6 == CTX | |
3026 | * | |
3027 | * Explicit input: | |
3028 | * SRC == any register | |
3029 | * IMM == 32-bit immediate | |
3030 | * | |
3031 | * Output: | |
3032 | * R0 - 8/16/32-bit skb data converted to cpu endianness | |
3033 | */ | |
58e2af8b | 3034 | static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) |
ddd872bc | 3035 | { |
58e2af8b | 3036 | struct bpf_reg_state *regs = env->cur_state.regs; |
ddd872bc | 3037 | u8 mode = BPF_MODE(insn->code); |
ddd872bc AS |
3038 | int i, err; |
3039 | ||
24701ece | 3040 | if (!may_access_skb(env->prog->type)) { |
1a0dc1ac | 3041 | verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); |
ddd872bc AS |
3042 | return -EINVAL; |
3043 | } | |
3044 | ||
3045 | if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || | |
d82bccc6 | 3046 | BPF_SIZE(insn->code) == BPF_DW || |
ddd872bc | 3047 | (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { |
1a0dc1ac | 3048 | verbose("BPF_LD_[ABS|IND] uses reserved fields\n"); |
ddd872bc AS |
3049 | return -EINVAL; |
3050 | } | |
3051 | ||
3052 | /* check whether implicit source operand (register R6) is readable */ | |
dc503a8a | 3053 | err = check_reg_arg(env, BPF_REG_6, SRC_OP); |
ddd872bc AS |
3054 | if (err) |
3055 | return err; | |
3056 | ||
3057 | if (regs[BPF_REG_6].type != PTR_TO_CTX) { | |
3058 | verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); | |
3059 | return -EINVAL; | |
3060 | } | |
3061 | ||
3062 | if (mode == BPF_IND) { | |
3063 | /* check explicit source operand */ | |
dc503a8a | 3064 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
ddd872bc AS |
3065 | if (err) |
3066 | return err; | |
3067 | } | |
3068 | ||
3069 | /* reset caller saved regs to unreadable */ | |
dc503a8a | 3070 | for (i = 0; i < CALLER_SAVED_REGS; i++) { |
a9789ef9 | 3071 | mark_reg_not_init(regs, caller_saved[i]); |
dc503a8a EC |
3072 | check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); |
3073 | } | |
ddd872bc AS |
3074 | |
3075 | /* mark destination R0 register as readable, since it contains | |
dc503a8a EC |
3076 | * the value fetched from the packet. |
3077 | * Already marked as written above. | |
ddd872bc | 3078 | */ |
f1174f77 | 3079 | mark_reg_unknown(regs, BPF_REG_0); |
ddd872bc AS |
3080 | return 0; |
3081 | } | |
3082 | ||
390ee7e2 AS |
3083 | static int check_return_code(struct bpf_verifier_env *env) |
3084 | { | |
3085 | struct bpf_reg_state *reg; | |
3086 | struct tnum range = tnum_range(0, 1); | |
3087 | ||
3088 | switch (env->prog->type) { | |
3089 | case BPF_PROG_TYPE_CGROUP_SKB: | |
3090 | case BPF_PROG_TYPE_CGROUP_SOCK: | |
3091 | case BPF_PROG_TYPE_SOCK_OPS: | |
3092 | break; | |
3093 | default: | |
3094 | return 0; | |
3095 | } | |
3096 | ||
3097 | reg = &env->cur_state.regs[BPF_REG_0]; | |
3098 | if (reg->type != SCALAR_VALUE) { | |
3099 | verbose("At program exit the register R0 is not a known value (%s)\n", | |
3100 | reg_type_str[reg->type]); | |
3101 | return -EINVAL; | |
3102 | } | |
3103 | ||
3104 | if (!tnum_in(range, reg->var_off)) { | |
3105 | verbose("At program exit the register R0 "); | |
3106 | if (!tnum_is_unknown(reg->var_off)) { | |
3107 | char tn_buf[48]; | |
3108 | ||
3109 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
3110 | verbose("has value %s", tn_buf); | |
3111 | } else { | |
3112 | verbose("has unknown scalar value"); | |
3113 | } | |
3114 | verbose(" should have been 0 or 1\n"); | |
3115 | return -EINVAL; | |
3116 | } | |
3117 | return 0; | |
3118 | } | |
3119 | ||
475fb78f AS |
3120 | /* non-recursive DFS pseudo code |
3121 | * 1 procedure DFS-iterative(G,v): | |
3122 | * 2 label v as discovered | |
3123 | * 3 let S be a stack | |
3124 | * 4 S.push(v) | |
3125 | * 5 while S is not empty | |
3126 | * 6 t <- S.pop() | |
3127 | * 7 if t is what we're looking for: | |
3128 | * 8 return t | |
3129 | * 9 for all edges e in G.adjacentEdges(t) do | |
3130 | * 10 if edge e is already labelled | |
3131 | * 11 continue with the next edge | |
3132 | * 12 w <- G.adjacentVertex(t,e) | |
3133 | * 13 if vertex w is not discovered and not explored | |
3134 | * 14 label e as tree-edge | |
3135 | * 15 label w as discovered | |
3136 | * 16 S.push(w) | |
3137 | * 17 continue at 5 | |
3138 | * 18 else if vertex w is discovered | |
3139 | * 19 label e as back-edge | |
3140 | * 20 else | |
3141 | * 21 // vertex w is explored | |
3142 | * 22 label e as forward- or cross-edge | |
3143 | * 23 label t as explored | |
3144 | * 24 S.pop() | |
3145 | * | |
3146 | * convention: | |
3147 | * 0x10 - discovered | |
3148 | * 0x11 - discovered and fall-through edge labelled | |
3149 | * 0x12 - discovered and fall-through and branch edges labelled | |
3150 | * 0x20 - explored | |
3151 | */ | |
3152 | ||
3153 | enum { | |
3154 | DISCOVERED = 0x10, | |
3155 | EXPLORED = 0x20, | |
3156 | FALLTHROUGH = 1, | |
3157 | BRANCH = 2, | |
3158 | }; | |
3159 | ||
58e2af8b | 3160 | #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L) |
f1bca824 | 3161 | |
475fb78f AS |
3162 | static int *insn_stack; /* stack of insns to process */ |
3163 | static int cur_stack; /* current stack index */ | |
3164 | static int *insn_state; | |
3165 | ||
3166 | /* t, w, e - match pseudo-code above: | |
3167 | * t - index of current instruction | |
3168 | * w - next instruction | |
3169 | * e - edge | |
3170 | */ | |
58e2af8b | 3171 | static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) |
475fb78f AS |
3172 | { |
3173 | if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) | |
3174 | return 0; | |
3175 | ||
3176 | if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) | |
3177 | return 0; | |
3178 | ||
3179 | if (w < 0 || w >= env->prog->len) { | |
3180 | verbose("jump out of range from insn %d to %d\n", t, w); | |
3181 | return -EINVAL; | |
3182 | } | |
3183 | ||
f1bca824 AS |
3184 | if (e == BRANCH) |
3185 | /* mark branch target for state pruning */ | |
3186 | env->explored_states[w] = STATE_LIST_MARK; | |
3187 | ||
475fb78f AS |
3188 | if (insn_state[w] == 0) { |
3189 | /* tree-edge */ | |
3190 | insn_state[t] = DISCOVERED | e; | |
3191 | insn_state[w] = DISCOVERED; | |
3192 | if (cur_stack >= env->prog->len) | |
3193 | return -E2BIG; | |
3194 | insn_stack[cur_stack++] = w; | |
3195 | return 1; | |
3196 | } else if ((insn_state[w] & 0xF0) == DISCOVERED) { | |
3197 | verbose("back-edge from insn %d to %d\n", t, w); | |
3198 | return -EINVAL; | |
3199 | } else if (insn_state[w] == EXPLORED) { | |
3200 | /* forward- or cross-edge */ | |
3201 | insn_state[t] = DISCOVERED | e; | |
3202 | } else { | |
3203 | verbose("insn state internal bug\n"); | |
3204 | return -EFAULT; | |
3205 | } | |
3206 | return 0; | |
3207 | } | |
3208 | ||
3209 | /* non-recursive depth-first-search to detect loops in BPF program | |
3210 | * loop == back-edge in directed graph | |
3211 | */ | |
58e2af8b | 3212 | static int check_cfg(struct bpf_verifier_env *env) |
475fb78f AS |
3213 | { |
3214 | struct bpf_insn *insns = env->prog->insnsi; | |
3215 | int insn_cnt = env->prog->len; | |
3216 | int ret = 0; | |
3217 | int i, t; | |
3218 | ||
3219 | insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
3220 | if (!insn_state) | |
3221 | return -ENOMEM; | |
3222 | ||
3223 | insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
3224 | if (!insn_stack) { | |
3225 | kfree(insn_state); | |
3226 | return -ENOMEM; | |
3227 | } | |
3228 | ||
3229 | insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ | |
3230 | insn_stack[0] = 0; /* 0 is the first instruction */ | |
3231 | cur_stack = 1; | |
3232 | ||
3233 | peek_stack: | |
3234 | if (cur_stack == 0) | |
3235 | goto check_state; | |
3236 | t = insn_stack[cur_stack - 1]; | |
3237 | ||
3238 | if (BPF_CLASS(insns[t].code) == BPF_JMP) { | |
3239 | u8 opcode = BPF_OP(insns[t].code); | |
3240 | ||
3241 | if (opcode == BPF_EXIT) { | |
3242 | goto mark_explored; | |
3243 | } else if (opcode == BPF_CALL) { | |
3244 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
3245 | if (ret == 1) | |
3246 | goto peek_stack; | |
3247 | else if (ret < 0) | |
3248 | goto err_free; | |
07016151 DB |
3249 | if (t + 1 < insn_cnt) |
3250 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
3251 | } else if (opcode == BPF_JA) { |
3252 | if (BPF_SRC(insns[t].code) != BPF_K) { | |
3253 | ret = -EINVAL; | |
3254 | goto err_free; | |
3255 | } | |
3256 | /* unconditional jump with single edge */ | |
3257 | ret = push_insn(t, t + insns[t].off + 1, | |
3258 | FALLTHROUGH, env); | |
3259 | if (ret == 1) | |
3260 | goto peek_stack; | |
3261 | else if (ret < 0) | |
3262 | goto err_free; | |
f1bca824 AS |
3263 | /* tell verifier to check for equivalent states |
3264 | * after every call and jump | |
3265 | */ | |
c3de6317 AS |
3266 | if (t + 1 < insn_cnt) |
3267 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
3268 | } else { |
3269 | /* conditional jump with two edges */ | |
3c2ce60b | 3270 | env->explored_states[t] = STATE_LIST_MARK; |
475fb78f AS |
3271 | ret = push_insn(t, t + 1, FALLTHROUGH, env); |
3272 | if (ret == 1) | |
3273 | goto peek_stack; | |
3274 | else if (ret < 0) | |
3275 | goto err_free; | |
3276 | ||
3277 | ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); | |
3278 | if (ret == 1) | |
3279 | goto peek_stack; | |
3280 | else if (ret < 0) | |
3281 | goto err_free; | |
3282 | } | |
3283 | } else { | |
3284 | /* all other non-branch instructions with single | |
3285 | * fall-through edge | |
3286 | */ | |
3287 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
3288 | if (ret == 1) | |
3289 | goto peek_stack; | |
3290 | else if (ret < 0) | |
3291 | goto err_free; | |
3292 | } | |
3293 | ||
3294 | mark_explored: | |
3295 | insn_state[t] = EXPLORED; | |
3296 | if (cur_stack-- <= 0) { | |
3297 | verbose("pop stack internal bug\n"); | |
3298 | ret = -EFAULT; | |
3299 | goto err_free; | |
3300 | } | |
3301 | goto peek_stack; | |
3302 | ||
3303 | check_state: | |
3304 | for (i = 0; i < insn_cnt; i++) { | |
3305 | if (insn_state[i] != EXPLORED) { | |
3306 | verbose("unreachable insn %d\n", i); | |
3307 | ret = -EINVAL; | |
3308 | goto err_free; | |
3309 | } | |
3310 | } | |
3311 | ret = 0; /* cfg looks good */ | |
3312 | ||
3313 | err_free: | |
3314 | kfree(insn_state); | |
3315 | kfree(insn_stack); | |
3316 | return ret; | |
3317 | } | |
3318 | ||
f1174f77 EC |
3319 | /* check %cur's range satisfies %old's */ |
3320 | static bool range_within(struct bpf_reg_state *old, | |
3321 | struct bpf_reg_state *cur) | |
3322 | { | |
b03c9f9f EC |
3323 | return old->umin_value <= cur->umin_value && |
3324 | old->umax_value >= cur->umax_value && | |
3325 | old->smin_value <= cur->smin_value && | |
3326 | old->smax_value >= cur->smax_value; | |
f1174f77 EC |
3327 | } |
3328 | ||
3329 | /* Maximum number of register states that can exist at once */ | |
3330 | #define ID_MAP_SIZE (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE) | |
3331 | struct idpair { | |
3332 | u32 old; | |
3333 | u32 cur; | |
3334 | }; | |
3335 | ||
3336 | /* If in the old state two registers had the same id, then they need to have | |
3337 | * the same id in the new state as well. But that id could be different from | |
3338 | * the old state, so we need to track the mapping from old to new ids. | |
3339 | * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent | |
3340 | * regs with old id 5 must also have new id 9 for the new state to be safe. But | |
3341 | * regs with a different old id could still have new id 9, we don't care about | |
3342 | * that. | |
3343 | * So we look through our idmap to see if this old id has been seen before. If | |
3344 | * so, we require the new id to match; otherwise, we add the id pair to the map. | |
969bf05e | 3345 | */ |
f1174f77 | 3346 | static bool check_ids(u32 old_id, u32 cur_id, struct idpair *idmap) |
969bf05e | 3347 | { |
f1174f77 | 3348 | unsigned int i; |
969bf05e | 3349 | |
f1174f77 EC |
3350 | for (i = 0; i < ID_MAP_SIZE; i++) { |
3351 | if (!idmap[i].old) { | |
3352 | /* Reached an empty slot; haven't seen this id before */ | |
3353 | idmap[i].old = old_id; | |
3354 | idmap[i].cur = cur_id; | |
3355 | return true; | |
3356 | } | |
3357 | if (idmap[i].old == old_id) | |
3358 | return idmap[i].cur == cur_id; | |
3359 | } | |
3360 | /* We ran out of idmap slots, which should be impossible */ | |
3361 | WARN_ON_ONCE(1); | |
3362 | return false; | |
3363 | } | |
3364 | ||
3365 | /* Returns true if (rold safe implies rcur safe) */ | |
1b688a19 EC |
3366 | static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, |
3367 | struct idpair *idmap) | |
f1174f77 | 3368 | { |
dc503a8a EC |
3369 | if (!(rold->live & REG_LIVE_READ)) |
3370 | /* explored state didn't use this */ | |
3371 | return true; | |
3372 | ||
3373 | if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, live)) == 0) | |
969bf05e AS |
3374 | return true; |
3375 | ||
f1174f77 EC |
3376 | if (rold->type == NOT_INIT) |
3377 | /* explored state can't have used this */ | |
969bf05e | 3378 | return true; |
f1174f77 EC |
3379 | if (rcur->type == NOT_INIT) |
3380 | return false; | |
3381 | switch (rold->type) { | |
3382 | case SCALAR_VALUE: | |
3383 | if (rcur->type == SCALAR_VALUE) { | |
3384 | /* new val must satisfy old val knowledge */ | |
3385 | return range_within(rold, rcur) && | |
3386 | tnum_in(rold->var_off, rcur->var_off); | |
3387 | } else { | |
3388 | /* if we knew anything about the old value, we're not | |
3389 | * equal, because we can't know anything about the | |
3390 | * scalar value of the pointer in the new value. | |
3391 | */ | |
b03c9f9f EC |
3392 | return rold->umin_value == 0 && |
3393 | rold->umax_value == U64_MAX && | |
3394 | rold->smin_value == S64_MIN && | |
3395 | rold->smax_value == S64_MAX && | |
f1174f77 EC |
3396 | tnum_is_unknown(rold->var_off); |
3397 | } | |
3398 | case PTR_TO_MAP_VALUE: | |
1b688a19 EC |
3399 | /* If the new min/max/var_off satisfy the old ones and |
3400 | * everything else matches, we are OK. | |
3401 | * We don't care about the 'id' value, because nothing | |
3402 | * uses it for PTR_TO_MAP_VALUE (only for ..._OR_NULL) | |
3403 | */ | |
3404 | return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && | |
3405 | range_within(rold, rcur) && | |
3406 | tnum_in(rold->var_off, rcur->var_off); | |
f1174f77 EC |
3407 | case PTR_TO_MAP_VALUE_OR_NULL: |
3408 | /* a PTR_TO_MAP_VALUE could be safe to use as a | |
3409 | * PTR_TO_MAP_VALUE_OR_NULL into the same map. | |
3410 | * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL- | |
3411 | * checked, doing so could have affected others with the same | |
3412 | * id, and we can't check for that because we lost the id when | |
3413 | * we converted to a PTR_TO_MAP_VALUE. | |
3414 | */ | |
3415 | if (rcur->type != PTR_TO_MAP_VALUE_OR_NULL) | |
3416 | return false; | |
3417 | if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id))) | |
3418 | return false; | |
3419 | /* Check our ids match any regs they're supposed to */ | |
3420 | return check_ids(rold->id, rcur->id, idmap); | |
de8f3a83 | 3421 | case PTR_TO_PACKET_META: |
f1174f77 | 3422 | case PTR_TO_PACKET: |
de8f3a83 | 3423 | if (rcur->type != rold->type) |
f1174f77 EC |
3424 | return false; |
3425 | /* We must have at least as much range as the old ptr | |
3426 | * did, so that any accesses which were safe before are | |
3427 | * still safe. This is true even if old range < old off, | |
3428 | * since someone could have accessed through (ptr - k), or | |
3429 | * even done ptr -= k in a register, to get a safe access. | |
3430 | */ | |
3431 | if (rold->range > rcur->range) | |
3432 | return false; | |
3433 | /* If the offsets don't match, we can't trust our alignment; | |
3434 | * nor can we be sure that we won't fall out of range. | |
3435 | */ | |
3436 | if (rold->off != rcur->off) | |
3437 | return false; | |
3438 | /* id relations must be preserved */ | |
3439 | if (rold->id && !check_ids(rold->id, rcur->id, idmap)) | |
3440 | return false; | |
3441 | /* new val must satisfy old val knowledge */ | |
3442 | return range_within(rold, rcur) && | |
3443 | tnum_in(rold->var_off, rcur->var_off); | |
3444 | case PTR_TO_CTX: | |
3445 | case CONST_PTR_TO_MAP: | |
3446 | case PTR_TO_STACK: | |
3447 | case PTR_TO_PACKET_END: | |
3448 | /* Only valid matches are exact, which memcmp() above | |
3449 | * would have accepted | |
3450 | */ | |
3451 | default: | |
3452 | /* Don't know what's going on, just say it's not safe */ | |
3453 | return false; | |
3454 | } | |
969bf05e | 3455 | |
f1174f77 EC |
3456 | /* Shouldn't get here; if we do, say it's not safe */ |
3457 | WARN_ON_ONCE(1); | |
969bf05e AS |
3458 | return false; |
3459 | } | |
3460 | ||
f1bca824 AS |
3461 | /* compare two verifier states |
3462 | * | |
3463 | * all states stored in state_list are known to be valid, since | |
3464 | * verifier reached 'bpf_exit' instruction through them | |
3465 | * | |
3466 | * this function is called when verifier exploring different branches of | |
3467 | * execution popped from the state stack. If it sees an old state that has | |
3468 | * more strict register state and more strict stack state then this execution | |
3469 | * branch doesn't need to be explored further, since verifier already | |
3470 | * concluded that more strict state leads to valid finish. | |
3471 | * | |
3472 | * Therefore two states are equivalent if register state is more conservative | |
3473 | * and explored stack state is more conservative than the current one. | |
3474 | * Example: | |
3475 | * explored current | |
3476 | * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) | |
3477 | * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) | |
3478 | * | |
3479 | * In other words if current stack state (one being explored) has more | |
3480 | * valid slots than old one that already passed validation, it means | |
3481 | * the verifier can stop exploring and conclude that current state is valid too | |
3482 | * | |
3483 | * Similarly with registers. If explored state has register type as invalid | |
3484 | * whereas register type in current state is meaningful, it means that | |
3485 | * the current state will reach 'bpf_exit' instruction safely | |
3486 | */ | |
48461135 JB |
3487 | static bool states_equal(struct bpf_verifier_env *env, |
3488 | struct bpf_verifier_state *old, | |
58e2af8b | 3489 | struct bpf_verifier_state *cur) |
f1bca824 | 3490 | { |
f1174f77 EC |
3491 | struct idpair *idmap; |
3492 | bool ret = false; | |
f1bca824 AS |
3493 | int i; |
3494 | ||
f1174f77 EC |
3495 | idmap = kcalloc(ID_MAP_SIZE, sizeof(struct idpair), GFP_KERNEL); |
3496 | /* If we failed to allocate the idmap, just say it's not safe */ | |
3497 | if (!idmap) | |
1a0dc1ac | 3498 | return false; |
f1174f77 EC |
3499 | |
3500 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1b688a19 | 3501 | if (!regsafe(&old->regs[i], &cur->regs[i], idmap)) |
f1174f77 | 3502 | goto out_free; |
f1bca824 AS |
3503 | } |
3504 | ||
3505 | for (i = 0; i < MAX_BPF_STACK; i++) { | |
9c399760 AS |
3506 | if (old->stack_slot_type[i] == STACK_INVALID) |
3507 | continue; | |
3508 | if (old->stack_slot_type[i] != cur->stack_slot_type[i]) | |
3509 | /* Ex: old explored (safe) state has STACK_SPILL in | |
3510 | * this stack slot, but current has has STACK_MISC -> | |
3511 | * this verifier states are not equivalent, | |
3512 | * return false to continue verification of this path | |
3513 | */ | |
f1174f77 | 3514 | goto out_free; |
9c399760 AS |
3515 | if (i % BPF_REG_SIZE) |
3516 | continue; | |
d25da6ca DB |
3517 | if (old->stack_slot_type[i] != STACK_SPILL) |
3518 | continue; | |
f1174f77 EC |
3519 | if (!regsafe(&old->spilled_regs[i / BPF_REG_SIZE], |
3520 | &cur->spilled_regs[i / BPF_REG_SIZE], | |
1b688a19 | 3521 | idmap)) |
f1174f77 EC |
3522 | /* when explored and current stack slot are both storing |
3523 | * spilled registers, check that stored pointers types | |
9c399760 AS |
3524 | * are the same as well. |
3525 | * Ex: explored safe path could have stored | |
f1174f77 | 3526 | * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8} |
9c399760 | 3527 | * but current path has stored: |
f1174f77 | 3528 | * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16} |
9c399760 AS |
3529 | * such verifier states are not equivalent. |
3530 | * return false to continue verification of this path | |
3531 | */ | |
f1174f77 | 3532 | goto out_free; |
9c399760 AS |
3533 | else |
3534 | continue; | |
f1bca824 | 3535 | } |
f1174f77 EC |
3536 | ret = true; |
3537 | out_free: | |
3538 | kfree(idmap); | |
3539 | return ret; | |
f1bca824 AS |
3540 | } |
3541 | ||
8e9cd9ce EC |
3542 | /* A write screens off any subsequent reads; but write marks come from the |
3543 | * straight-line code between a state and its parent. When we arrive at a | |
3544 | * jump target (in the first iteration of the propagate_liveness() loop), | |
3545 | * we didn't arrive by the straight-line code, so read marks in state must | |
3546 | * propagate to parent regardless of state's write marks. | |
3547 | */ | |
dc503a8a EC |
3548 | static bool do_propagate_liveness(const struct bpf_verifier_state *state, |
3549 | struct bpf_verifier_state *parent) | |
3550 | { | |
63f45f84 | 3551 | bool writes = parent == state->parent; /* Observe write marks */ |
dc503a8a EC |
3552 | bool touched = false; /* any changes made? */ |
3553 | int i; | |
3554 | ||
3555 | if (!parent) | |
3556 | return touched; | |
3557 | /* Propagate read liveness of registers... */ | |
3558 | BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); | |
3559 | /* We don't need to worry about FP liveness because it's read-only */ | |
3560 | for (i = 0; i < BPF_REG_FP; i++) { | |
3561 | if (parent->regs[i].live & REG_LIVE_READ) | |
3562 | continue; | |
63f45f84 EC |
3563 | if (writes && (state->regs[i].live & REG_LIVE_WRITTEN)) |
3564 | continue; | |
3565 | if (state->regs[i].live & REG_LIVE_READ) { | |
dc503a8a EC |
3566 | parent->regs[i].live |= REG_LIVE_READ; |
3567 | touched = true; | |
3568 | } | |
3569 | } | |
3570 | /* ... and stack slots */ | |
3571 | for (i = 0; i < MAX_BPF_STACK / BPF_REG_SIZE; i++) { | |
3572 | if (parent->stack_slot_type[i * BPF_REG_SIZE] != STACK_SPILL) | |
3573 | continue; | |
3574 | if (state->stack_slot_type[i * BPF_REG_SIZE] != STACK_SPILL) | |
3575 | continue; | |
3576 | if (parent->spilled_regs[i].live & REG_LIVE_READ) | |
3577 | continue; | |
63f45f84 EC |
3578 | if (writes && (state->spilled_regs[i].live & REG_LIVE_WRITTEN)) |
3579 | continue; | |
3580 | if (state->spilled_regs[i].live & REG_LIVE_READ) { | |
1ab2de2b | 3581 | parent->spilled_regs[i].live |= REG_LIVE_READ; |
dc503a8a EC |
3582 | touched = true; |
3583 | } | |
3584 | } | |
3585 | return touched; | |
3586 | } | |
3587 | ||
8e9cd9ce EC |
3588 | /* "parent" is "a state from which we reach the current state", but initially |
3589 | * it is not the state->parent (i.e. "the state whose straight-line code leads | |
3590 | * to the current state"), instead it is the state that happened to arrive at | |
3591 | * a (prunable) equivalent of the current state. See comment above | |
3592 | * do_propagate_liveness() for consequences of this. | |
3593 | * This function is just a more efficient way of calling mark_reg_read() or | |
3594 | * mark_stack_slot_read() on each reg in "parent" that is read in "state", | |
3595 | * though it requires that parent != state->parent in the call arguments. | |
3596 | */ | |
dc503a8a EC |
3597 | static void propagate_liveness(const struct bpf_verifier_state *state, |
3598 | struct bpf_verifier_state *parent) | |
3599 | { | |
3600 | while (do_propagate_liveness(state, parent)) { | |
3601 | /* Something changed, so we need to feed those changes onward */ | |
3602 | state = parent; | |
3603 | parent = state->parent; | |
3604 | } | |
3605 | } | |
3606 | ||
58e2af8b | 3607 | static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) |
f1bca824 | 3608 | { |
58e2af8b JK |
3609 | struct bpf_verifier_state_list *new_sl; |
3610 | struct bpf_verifier_state_list *sl; | |
dc503a8a | 3611 | int i; |
f1bca824 AS |
3612 | |
3613 | sl = env->explored_states[insn_idx]; | |
3614 | if (!sl) | |
3615 | /* this 'insn_idx' instruction wasn't marked, so we will not | |
3616 | * be doing state search here | |
3617 | */ | |
3618 | return 0; | |
3619 | ||
3620 | while (sl != STATE_LIST_MARK) { | |
dc503a8a | 3621 | if (states_equal(env, &sl->state, &env->cur_state)) { |
f1bca824 | 3622 | /* reached equivalent register/stack state, |
dc503a8a EC |
3623 | * prune the search. |
3624 | * Registers read by the continuation are read by us. | |
8e9cd9ce EC |
3625 | * If we have any write marks in env->cur_state, they |
3626 | * will prevent corresponding reads in the continuation | |
3627 | * from reaching our parent (an explored_state). Our | |
3628 | * own state will get the read marks recorded, but | |
3629 | * they'll be immediately forgotten as we're pruning | |
3630 | * this state and will pop a new one. | |
f1bca824 | 3631 | */ |
dc503a8a | 3632 | propagate_liveness(&sl->state, &env->cur_state); |
f1bca824 | 3633 | return 1; |
dc503a8a | 3634 | } |
f1bca824 AS |
3635 | sl = sl->next; |
3636 | } | |
3637 | ||
3638 | /* there were no equivalent states, remember current one. | |
3639 | * technically the current state is not proven to be safe yet, | |
3640 | * but it will either reach bpf_exit (which means it's safe) or | |
3641 | * it will be rejected. Since there are no loops, we won't be | |
3642 | * seeing this 'insn_idx' instruction again on the way to bpf_exit | |
3643 | */ | |
58e2af8b | 3644 | new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER); |
f1bca824 AS |
3645 | if (!new_sl) |
3646 | return -ENOMEM; | |
3647 | ||
3648 | /* add new state to the head of linked list */ | |
3649 | memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); | |
3650 | new_sl->next = env->explored_states[insn_idx]; | |
3651 | env->explored_states[insn_idx] = new_sl; | |
dc503a8a EC |
3652 | /* connect new state to parentage chain */ |
3653 | env->cur_state.parent = &new_sl->state; | |
8e9cd9ce EC |
3654 | /* clear write marks in current state: the writes we did are not writes |
3655 | * our child did, so they don't screen off its reads from us. | |
3656 | * (There are no read marks in current state, because reads always mark | |
3657 | * their parent and current state never has children yet. Only | |
3658 | * explored_states can get read marks.) | |
3659 | */ | |
dc503a8a EC |
3660 | for (i = 0; i < BPF_REG_FP; i++) |
3661 | env->cur_state.regs[i].live = REG_LIVE_NONE; | |
3662 | for (i = 0; i < MAX_BPF_STACK / BPF_REG_SIZE; i++) | |
3663 | if (env->cur_state.stack_slot_type[i * BPF_REG_SIZE] == STACK_SPILL) | |
3664 | env->cur_state.spilled_regs[i].live = REG_LIVE_NONE; | |
f1bca824 AS |
3665 | return 0; |
3666 | } | |
3667 | ||
13a27dfc JK |
3668 | static int ext_analyzer_insn_hook(struct bpf_verifier_env *env, |
3669 | int insn_idx, int prev_insn_idx) | |
3670 | { | |
3671 | if (!env->analyzer_ops || !env->analyzer_ops->insn_hook) | |
3672 | return 0; | |
3673 | ||
3674 | return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx); | |
3675 | } | |
3676 | ||
58e2af8b | 3677 | static int do_check(struct bpf_verifier_env *env) |
17a52670 | 3678 | { |
58e2af8b | 3679 | struct bpf_verifier_state *state = &env->cur_state; |
17a52670 | 3680 | struct bpf_insn *insns = env->prog->insnsi; |
58e2af8b | 3681 | struct bpf_reg_state *regs = state->regs; |
17a52670 AS |
3682 | int insn_cnt = env->prog->len; |
3683 | int insn_idx, prev_insn_idx = 0; | |
3684 | int insn_processed = 0; | |
3685 | bool do_print_state = false; | |
3686 | ||
3687 | init_reg_state(regs); | |
dc503a8a | 3688 | state->parent = NULL; |
17a52670 AS |
3689 | insn_idx = 0; |
3690 | for (;;) { | |
3691 | struct bpf_insn *insn; | |
3692 | u8 class; | |
3693 | int err; | |
3694 | ||
3695 | if (insn_idx >= insn_cnt) { | |
3696 | verbose("invalid insn idx %d insn_cnt %d\n", | |
3697 | insn_idx, insn_cnt); | |
3698 | return -EFAULT; | |
3699 | } | |
3700 | ||
3701 | insn = &insns[insn_idx]; | |
3702 | class = BPF_CLASS(insn->code); | |
3703 | ||
07016151 | 3704 | if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { |
bc1750f3 | 3705 | verbose("BPF program is too large. Processed %d insn\n", |
17a52670 AS |
3706 | insn_processed); |
3707 | return -E2BIG; | |
3708 | } | |
3709 | ||
f1bca824 AS |
3710 | err = is_state_visited(env, insn_idx); |
3711 | if (err < 0) | |
3712 | return err; | |
3713 | if (err == 1) { | |
3714 | /* found equivalent state, can prune the search */ | |
3715 | if (log_level) { | |
3716 | if (do_print_state) | |
3717 | verbose("\nfrom %d to %d: safe\n", | |
3718 | prev_insn_idx, insn_idx); | |
3719 | else | |
3720 | verbose("%d: safe\n", insn_idx); | |
3721 | } | |
3722 | goto process_bpf_exit; | |
3723 | } | |
3724 | ||
3c2ce60b DB |
3725 | if (need_resched()) |
3726 | cond_resched(); | |
3727 | ||
c5fc9692 DM |
3728 | if (log_level > 1 || (log_level && do_print_state)) { |
3729 | if (log_level > 1) | |
3730 | verbose("%d:", insn_idx); | |
3731 | else | |
3732 | verbose("\nfrom %d to %d:", | |
3733 | prev_insn_idx, insn_idx); | |
1a0dc1ac | 3734 | print_verifier_state(&env->cur_state); |
17a52670 AS |
3735 | do_print_state = false; |
3736 | } | |
3737 | ||
3738 | if (log_level) { | |
3739 | verbose("%d: ", insn_idx); | |
0d0e5769 | 3740 | print_bpf_insn(env, insn); |
17a52670 AS |
3741 | } |
3742 | ||
13a27dfc JK |
3743 | err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx); |
3744 | if (err) | |
3745 | return err; | |
3746 | ||
17a52670 | 3747 | if (class == BPF_ALU || class == BPF_ALU64) { |
1be7f75d | 3748 | err = check_alu_op(env, insn); |
17a52670 AS |
3749 | if (err) |
3750 | return err; | |
3751 | ||
3752 | } else if (class == BPF_LDX) { | |
3df126f3 | 3753 | enum bpf_reg_type *prev_src_type, src_reg_type; |
9bac3d6d AS |
3754 | |
3755 | /* check for reserved fields is already done */ | |
3756 | ||
17a52670 | 3757 | /* check src operand */ |
dc503a8a | 3758 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
3759 | if (err) |
3760 | return err; | |
3761 | ||
dc503a8a | 3762 | err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); |
17a52670 AS |
3763 | if (err) |
3764 | return err; | |
3765 | ||
725f9dcd AS |
3766 | src_reg_type = regs[insn->src_reg].type; |
3767 | ||
17a52670 AS |
3768 | /* check that memory (src_reg + off) is readable, |
3769 | * the state of dst_reg will be updated by this func | |
3770 | */ | |
31fd8581 | 3771 | err = check_mem_access(env, insn_idx, insn->src_reg, insn->off, |
17a52670 AS |
3772 | BPF_SIZE(insn->code), BPF_READ, |
3773 | insn->dst_reg); | |
3774 | if (err) | |
3775 | return err; | |
3776 | ||
3df126f3 JK |
3777 | prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; |
3778 | ||
3779 | if (*prev_src_type == NOT_INIT) { | |
9bac3d6d AS |
3780 | /* saw a valid insn |
3781 | * dst_reg = *(u32 *)(src_reg + off) | |
3df126f3 | 3782 | * save type to validate intersecting paths |
9bac3d6d | 3783 | */ |
3df126f3 | 3784 | *prev_src_type = src_reg_type; |
9bac3d6d | 3785 | |
3df126f3 | 3786 | } else if (src_reg_type != *prev_src_type && |
9bac3d6d | 3787 | (src_reg_type == PTR_TO_CTX || |
3df126f3 | 3788 | *prev_src_type == PTR_TO_CTX)) { |
9bac3d6d AS |
3789 | /* ABuser program is trying to use the same insn |
3790 | * dst_reg = *(u32*) (src_reg + off) | |
3791 | * with different pointer types: | |
3792 | * src_reg == ctx in one branch and | |
3793 | * src_reg == stack|map in some other branch. | |
3794 | * Reject it. | |
3795 | */ | |
3796 | verbose("same insn cannot be used with different pointers\n"); | |
3797 | return -EINVAL; | |
3798 | } | |
3799 | ||
17a52670 | 3800 | } else if (class == BPF_STX) { |
3df126f3 | 3801 | enum bpf_reg_type *prev_dst_type, dst_reg_type; |
d691f9e8 | 3802 | |
17a52670 | 3803 | if (BPF_MODE(insn->code) == BPF_XADD) { |
31fd8581 | 3804 | err = check_xadd(env, insn_idx, insn); |
17a52670 AS |
3805 | if (err) |
3806 | return err; | |
3807 | insn_idx++; | |
3808 | continue; | |
3809 | } | |
3810 | ||
17a52670 | 3811 | /* check src1 operand */ |
dc503a8a | 3812 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
3813 | if (err) |
3814 | return err; | |
3815 | /* check src2 operand */ | |
dc503a8a | 3816 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
3817 | if (err) |
3818 | return err; | |
3819 | ||
d691f9e8 AS |
3820 | dst_reg_type = regs[insn->dst_reg].type; |
3821 | ||
17a52670 | 3822 | /* check that memory (dst_reg + off) is writeable */ |
31fd8581 | 3823 | err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
3824 | BPF_SIZE(insn->code), BPF_WRITE, |
3825 | insn->src_reg); | |
3826 | if (err) | |
3827 | return err; | |
3828 | ||
3df126f3 JK |
3829 | prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type; |
3830 | ||
3831 | if (*prev_dst_type == NOT_INIT) { | |
3832 | *prev_dst_type = dst_reg_type; | |
3833 | } else if (dst_reg_type != *prev_dst_type && | |
d691f9e8 | 3834 | (dst_reg_type == PTR_TO_CTX || |
3df126f3 | 3835 | *prev_dst_type == PTR_TO_CTX)) { |
d691f9e8 AS |
3836 | verbose("same insn cannot be used with different pointers\n"); |
3837 | return -EINVAL; | |
3838 | } | |
3839 | ||
17a52670 AS |
3840 | } else if (class == BPF_ST) { |
3841 | if (BPF_MODE(insn->code) != BPF_MEM || | |
3842 | insn->src_reg != BPF_REG_0) { | |
3843 | verbose("BPF_ST uses reserved fields\n"); | |
3844 | return -EINVAL; | |
3845 | } | |
3846 | /* check src operand */ | |
dc503a8a | 3847 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
3848 | if (err) |
3849 | return err; | |
3850 | ||
3851 | /* check that memory (dst_reg + off) is writeable */ | |
31fd8581 | 3852 | err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
3853 | BPF_SIZE(insn->code), BPF_WRITE, |
3854 | -1); | |
3855 | if (err) | |
3856 | return err; | |
3857 | ||
3858 | } else if (class == BPF_JMP) { | |
3859 | u8 opcode = BPF_OP(insn->code); | |
3860 | ||
3861 | if (opcode == BPF_CALL) { | |
3862 | if (BPF_SRC(insn->code) != BPF_K || | |
3863 | insn->off != 0 || | |
3864 | insn->src_reg != BPF_REG_0 || | |
3865 | insn->dst_reg != BPF_REG_0) { | |
3866 | verbose("BPF_CALL uses reserved fields\n"); | |
3867 | return -EINVAL; | |
3868 | } | |
3869 | ||
81ed18ab | 3870 | err = check_call(env, insn->imm, insn_idx); |
17a52670 AS |
3871 | if (err) |
3872 | return err; | |
3873 | ||
3874 | } else if (opcode == BPF_JA) { | |
3875 | if (BPF_SRC(insn->code) != BPF_K || | |
3876 | insn->imm != 0 || | |
3877 | insn->src_reg != BPF_REG_0 || | |
3878 | insn->dst_reg != BPF_REG_0) { | |
3879 | verbose("BPF_JA uses reserved fields\n"); | |
3880 | return -EINVAL; | |
3881 | } | |
3882 | ||
3883 | insn_idx += insn->off + 1; | |
3884 | continue; | |
3885 | ||
3886 | } else if (opcode == BPF_EXIT) { | |
3887 | if (BPF_SRC(insn->code) != BPF_K || | |
3888 | insn->imm != 0 || | |
3889 | insn->src_reg != BPF_REG_0 || | |
3890 | insn->dst_reg != BPF_REG_0) { | |
3891 | verbose("BPF_EXIT uses reserved fields\n"); | |
3892 | return -EINVAL; | |
3893 | } | |
3894 | ||
3895 | /* eBPF calling convetion is such that R0 is used | |
3896 | * to return the value from eBPF program. | |
3897 | * Make sure that it's readable at this time | |
3898 | * of bpf_exit, which means that program wrote | |
3899 | * something into it earlier | |
3900 | */ | |
dc503a8a | 3901 | err = check_reg_arg(env, BPF_REG_0, SRC_OP); |
17a52670 AS |
3902 | if (err) |
3903 | return err; | |
3904 | ||
1be7f75d AS |
3905 | if (is_pointer_value(env, BPF_REG_0)) { |
3906 | verbose("R0 leaks addr as return value\n"); | |
3907 | return -EACCES; | |
3908 | } | |
3909 | ||
390ee7e2 AS |
3910 | err = check_return_code(env); |
3911 | if (err) | |
3912 | return err; | |
f1bca824 | 3913 | process_bpf_exit: |
17a52670 AS |
3914 | insn_idx = pop_stack(env, &prev_insn_idx); |
3915 | if (insn_idx < 0) { | |
3916 | break; | |
3917 | } else { | |
3918 | do_print_state = true; | |
3919 | continue; | |
3920 | } | |
3921 | } else { | |
3922 | err = check_cond_jmp_op(env, insn, &insn_idx); | |
3923 | if (err) | |
3924 | return err; | |
3925 | } | |
3926 | } else if (class == BPF_LD) { | |
3927 | u8 mode = BPF_MODE(insn->code); | |
3928 | ||
3929 | if (mode == BPF_ABS || mode == BPF_IND) { | |
ddd872bc AS |
3930 | err = check_ld_abs(env, insn); |
3931 | if (err) | |
3932 | return err; | |
3933 | ||
17a52670 AS |
3934 | } else if (mode == BPF_IMM) { |
3935 | err = check_ld_imm(env, insn); | |
3936 | if (err) | |
3937 | return err; | |
3938 | ||
3939 | insn_idx++; | |
3940 | } else { | |
3941 | verbose("invalid BPF_LD mode\n"); | |
3942 | return -EINVAL; | |
3943 | } | |
3944 | } else { | |
3945 | verbose("unknown insn class %d\n", class); | |
3946 | return -EINVAL; | |
3947 | } | |
3948 | ||
3949 | insn_idx++; | |
3950 | } | |
3951 | ||
8726679a AS |
3952 | verbose("processed %d insns, stack depth %d\n", |
3953 | insn_processed, env->prog->aux->stack_depth); | |
17a52670 AS |
3954 | return 0; |
3955 | } | |
3956 | ||
56f668df MKL |
3957 | static int check_map_prealloc(struct bpf_map *map) |
3958 | { | |
3959 | return (map->map_type != BPF_MAP_TYPE_HASH && | |
bcc6b1b7 MKL |
3960 | map->map_type != BPF_MAP_TYPE_PERCPU_HASH && |
3961 | map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) || | |
56f668df MKL |
3962 | !(map->map_flags & BPF_F_NO_PREALLOC); |
3963 | } | |
3964 | ||
fdc15d38 AS |
3965 | static int check_map_prog_compatibility(struct bpf_map *map, |
3966 | struct bpf_prog *prog) | |
3967 | ||
3968 | { | |
56f668df MKL |
3969 | /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use |
3970 | * preallocated hash maps, since doing memory allocation | |
3971 | * in overflow_handler can crash depending on where nmi got | |
3972 | * triggered. | |
3973 | */ | |
3974 | if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { | |
3975 | if (!check_map_prealloc(map)) { | |
3976 | verbose("perf_event programs can only use preallocated hash map\n"); | |
3977 | return -EINVAL; | |
3978 | } | |
3979 | if (map->inner_map_meta && | |
3980 | !check_map_prealloc(map->inner_map_meta)) { | |
3981 | verbose("perf_event programs can only use preallocated inner hash map\n"); | |
3982 | return -EINVAL; | |
3983 | } | |
fdc15d38 AS |
3984 | } |
3985 | return 0; | |
3986 | } | |
3987 | ||
0246e64d AS |
3988 | /* look for pseudo eBPF instructions that access map FDs and |
3989 | * replace them with actual map pointers | |
3990 | */ | |
58e2af8b | 3991 | static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) |
0246e64d AS |
3992 | { |
3993 | struct bpf_insn *insn = env->prog->insnsi; | |
3994 | int insn_cnt = env->prog->len; | |
fdc15d38 | 3995 | int i, j, err; |
0246e64d | 3996 | |
f1f7714e | 3997 | err = bpf_prog_calc_tag(env->prog); |
aafe6ae9 DB |
3998 | if (err) |
3999 | return err; | |
4000 | ||
0246e64d | 4001 | for (i = 0; i < insn_cnt; i++, insn++) { |
9bac3d6d | 4002 | if (BPF_CLASS(insn->code) == BPF_LDX && |
d691f9e8 | 4003 | (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { |
9bac3d6d AS |
4004 | verbose("BPF_LDX uses reserved fields\n"); |
4005 | return -EINVAL; | |
4006 | } | |
4007 | ||
d691f9e8 AS |
4008 | if (BPF_CLASS(insn->code) == BPF_STX && |
4009 | ((BPF_MODE(insn->code) != BPF_MEM && | |
4010 | BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { | |
4011 | verbose("BPF_STX uses reserved fields\n"); | |
4012 | return -EINVAL; | |
4013 | } | |
4014 | ||
0246e64d AS |
4015 | if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { |
4016 | struct bpf_map *map; | |
4017 | struct fd f; | |
4018 | ||
4019 | if (i == insn_cnt - 1 || insn[1].code != 0 || | |
4020 | insn[1].dst_reg != 0 || insn[1].src_reg != 0 || | |
4021 | insn[1].off != 0) { | |
4022 | verbose("invalid bpf_ld_imm64 insn\n"); | |
4023 | return -EINVAL; | |
4024 | } | |
4025 | ||
4026 | if (insn->src_reg == 0) | |
4027 | /* valid generic load 64-bit imm */ | |
4028 | goto next_insn; | |
4029 | ||
4030 | if (insn->src_reg != BPF_PSEUDO_MAP_FD) { | |
4031 | verbose("unrecognized bpf_ld_imm64 insn\n"); | |
4032 | return -EINVAL; | |
4033 | } | |
4034 | ||
4035 | f = fdget(insn->imm); | |
c2101297 | 4036 | map = __bpf_map_get(f); |
0246e64d AS |
4037 | if (IS_ERR(map)) { |
4038 | verbose("fd %d is not pointing to valid bpf_map\n", | |
4039 | insn->imm); | |
0246e64d AS |
4040 | return PTR_ERR(map); |
4041 | } | |
4042 | ||
fdc15d38 AS |
4043 | err = check_map_prog_compatibility(map, env->prog); |
4044 | if (err) { | |
4045 | fdput(f); | |
4046 | return err; | |
4047 | } | |
4048 | ||
0246e64d AS |
4049 | /* store map pointer inside BPF_LD_IMM64 instruction */ |
4050 | insn[0].imm = (u32) (unsigned long) map; | |
4051 | insn[1].imm = ((u64) (unsigned long) map) >> 32; | |
4052 | ||
4053 | /* check whether we recorded this map already */ | |
4054 | for (j = 0; j < env->used_map_cnt; j++) | |
4055 | if (env->used_maps[j] == map) { | |
4056 | fdput(f); | |
4057 | goto next_insn; | |
4058 | } | |
4059 | ||
4060 | if (env->used_map_cnt >= MAX_USED_MAPS) { | |
4061 | fdput(f); | |
4062 | return -E2BIG; | |
4063 | } | |
4064 | ||
0246e64d AS |
4065 | /* hold the map. If the program is rejected by verifier, |
4066 | * the map will be released by release_maps() or it | |
4067 | * will be used by the valid program until it's unloaded | |
4068 | * and all maps are released in free_bpf_prog_info() | |
4069 | */ | |
92117d84 AS |
4070 | map = bpf_map_inc(map, false); |
4071 | if (IS_ERR(map)) { | |
4072 | fdput(f); | |
4073 | return PTR_ERR(map); | |
4074 | } | |
4075 | env->used_maps[env->used_map_cnt++] = map; | |
4076 | ||
0246e64d AS |
4077 | fdput(f); |
4078 | next_insn: | |
4079 | insn++; | |
4080 | i++; | |
4081 | } | |
4082 | } | |
4083 | ||
4084 | /* now all pseudo BPF_LD_IMM64 instructions load valid | |
4085 | * 'struct bpf_map *' into a register instead of user map_fd. | |
4086 | * These pointers will be used later by verifier to validate map access. | |
4087 | */ | |
4088 | return 0; | |
4089 | } | |
4090 | ||
4091 | /* drop refcnt of maps used by the rejected program */ | |
58e2af8b | 4092 | static void release_maps(struct bpf_verifier_env *env) |
0246e64d AS |
4093 | { |
4094 | int i; | |
4095 | ||
4096 | for (i = 0; i < env->used_map_cnt; i++) | |
4097 | bpf_map_put(env->used_maps[i]); | |
4098 | } | |
4099 | ||
4100 | /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ | |
58e2af8b | 4101 | static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) |
0246e64d AS |
4102 | { |
4103 | struct bpf_insn *insn = env->prog->insnsi; | |
4104 | int insn_cnt = env->prog->len; | |
4105 | int i; | |
4106 | ||
4107 | for (i = 0; i < insn_cnt; i++, insn++) | |
4108 | if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) | |
4109 | insn->src_reg = 0; | |
4110 | } | |
4111 | ||
8041902d AS |
4112 | /* single env->prog->insni[off] instruction was replaced with the range |
4113 | * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying | |
4114 | * [0, off) and [off, end) to new locations, so the patched range stays zero | |
4115 | */ | |
4116 | static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len, | |
4117 | u32 off, u32 cnt) | |
4118 | { | |
4119 | struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data; | |
4120 | ||
4121 | if (cnt == 1) | |
4122 | return 0; | |
4123 | new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len); | |
4124 | if (!new_data) | |
4125 | return -ENOMEM; | |
4126 | memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off); | |
4127 | memcpy(new_data + off + cnt - 1, old_data + off, | |
4128 | sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1)); | |
4129 | env->insn_aux_data = new_data; | |
4130 | vfree(old_data); | |
4131 | return 0; | |
4132 | } | |
4133 | ||
4134 | static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, | |
4135 | const struct bpf_insn *patch, u32 len) | |
4136 | { | |
4137 | struct bpf_prog *new_prog; | |
4138 | ||
4139 | new_prog = bpf_patch_insn_single(env->prog, off, patch, len); | |
4140 | if (!new_prog) | |
4141 | return NULL; | |
4142 | if (adjust_insn_aux_data(env, new_prog->len, off, len)) | |
4143 | return NULL; | |
4144 | return new_prog; | |
4145 | } | |
4146 | ||
9bac3d6d AS |
4147 | /* convert load instructions that access fields of 'struct __sk_buff' |
4148 | * into sequence of instructions that access fields of 'struct sk_buff' | |
4149 | */ | |
58e2af8b | 4150 | static int convert_ctx_accesses(struct bpf_verifier_env *env) |
9bac3d6d | 4151 | { |
36bbef52 | 4152 | const struct bpf_verifier_ops *ops = env->prog->aux->ops; |
f96da094 | 4153 | int i, cnt, size, ctx_field_size, delta = 0; |
3df126f3 | 4154 | const int insn_cnt = env->prog->len; |
36bbef52 | 4155 | struct bpf_insn insn_buf[16], *insn; |
9bac3d6d | 4156 | struct bpf_prog *new_prog; |
d691f9e8 | 4157 | enum bpf_access_type type; |
f96da094 DB |
4158 | bool is_narrower_load; |
4159 | u32 target_size; | |
9bac3d6d | 4160 | |
36bbef52 DB |
4161 | if (ops->gen_prologue) { |
4162 | cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, | |
4163 | env->prog); | |
4164 | if (cnt >= ARRAY_SIZE(insn_buf)) { | |
4165 | verbose("bpf verifier is misconfigured\n"); | |
4166 | return -EINVAL; | |
4167 | } else if (cnt) { | |
8041902d | 4168 | new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt); |
36bbef52 DB |
4169 | if (!new_prog) |
4170 | return -ENOMEM; | |
8041902d | 4171 | |
36bbef52 | 4172 | env->prog = new_prog; |
3df126f3 | 4173 | delta += cnt - 1; |
36bbef52 DB |
4174 | } |
4175 | } | |
4176 | ||
4177 | if (!ops->convert_ctx_access) | |
9bac3d6d AS |
4178 | return 0; |
4179 | ||
3df126f3 | 4180 | insn = env->prog->insnsi + delta; |
36bbef52 | 4181 | |
9bac3d6d | 4182 | for (i = 0; i < insn_cnt; i++, insn++) { |
62c7989b DB |
4183 | if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || |
4184 | insn->code == (BPF_LDX | BPF_MEM | BPF_H) || | |
4185 | insn->code == (BPF_LDX | BPF_MEM | BPF_W) || | |
ea2e7ce5 | 4186 | insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) |
d691f9e8 | 4187 | type = BPF_READ; |
62c7989b DB |
4188 | else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || |
4189 | insn->code == (BPF_STX | BPF_MEM | BPF_H) || | |
4190 | insn->code == (BPF_STX | BPF_MEM | BPF_W) || | |
ea2e7ce5 | 4191 | insn->code == (BPF_STX | BPF_MEM | BPF_DW)) |
d691f9e8 AS |
4192 | type = BPF_WRITE; |
4193 | else | |
9bac3d6d AS |
4194 | continue; |
4195 | ||
8041902d | 4196 | if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX) |
9bac3d6d | 4197 | continue; |
9bac3d6d | 4198 | |
31fd8581 | 4199 | ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; |
f96da094 | 4200 | size = BPF_LDST_BYTES(insn); |
31fd8581 YS |
4201 | |
4202 | /* If the read access is a narrower load of the field, | |
4203 | * convert to a 4/8-byte load, to minimum program type specific | |
4204 | * convert_ctx_access changes. If conversion is successful, | |
4205 | * we will apply proper mask to the result. | |
4206 | */ | |
f96da094 | 4207 | is_narrower_load = size < ctx_field_size; |
31fd8581 | 4208 | if (is_narrower_load) { |
f96da094 DB |
4209 | u32 off = insn->off; |
4210 | u8 size_code; | |
4211 | ||
4212 | if (type == BPF_WRITE) { | |
4213 | verbose("bpf verifier narrow ctx access misconfigured\n"); | |
4214 | return -EINVAL; | |
4215 | } | |
31fd8581 | 4216 | |
f96da094 | 4217 | size_code = BPF_H; |
31fd8581 YS |
4218 | if (ctx_field_size == 4) |
4219 | size_code = BPF_W; | |
4220 | else if (ctx_field_size == 8) | |
4221 | size_code = BPF_DW; | |
f96da094 | 4222 | |
31fd8581 YS |
4223 | insn->off = off & ~(ctx_field_size - 1); |
4224 | insn->code = BPF_LDX | BPF_MEM | size_code; | |
4225 | } | |
f96da094 DB |
4226 | |
4227 | target_size = 0; | |
4228 | cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog, | |
4229 | &target_size); | |
4230 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) || | |
4231 | (ctx_field_size && !target_size)) { | |
9bac3d6d AS |
4232 | verbose("bpf verifier is misconfigured\n"); |
4233 | return -EINVAL; | |
4234 | } | |
f96da094 DB |
4235 | |
4236 | if (is_narrower_load && size < target_size) { | |
31fd8581 YS |
4237 | if (ctx_field_size <= 4) |
4238 | insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, | |
f96da094 | 4239 | (1 << size * 8) - 1); |
31fd8581 YS |
4240 | else |
4241 | insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg, | |
f96da094 | 4242 | (1 << size * 8) - 1); |
31fd8581 | 4243 | } |
9bac3d6d | 4244 | |
8041902d | 4245 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); |
9bac3d6d AS |
4246 | if (!new_prog) |
4247 | return -ENOMEM; | |
4248 | ||
3df126f3 | 4249 | delta += cnt - 1; |
9bac3d6d AS |
4250 | |
4251 | /* keep walking new program and skip insns we just inserted */ | |
4252 | env->prog = new_prog; | |
3df126f3 | 4253 | insn = new_prog->insnsi + i + delta; |
9bac3d6d AS |
4254 | } |
4255 | ||
4256 | return 0; | |
4257 | } | |
4258 | ||
79741b3b | 4259 | /* fixup insn->imm field of bpf_call instructions |
81ed18ab | 4260 | * and inline eligible helpers as explicit sequence of BPF instructions |
e245c5c6 AS |
4261 | * |
4262 | * this function is called after eBPF program passed verification | |
4263 | */ | |
79741b3b | 4264 | static int fixup_bpf_calls(struct bpf_verifier_env *env) |
e245c5c6 | 4265 | { |
79741b3b AS |
4266 | struct bpf_prog *prog = env->prog; |
4267 | struct bpf_insn *insn = prog->insnsi; | |
e245c5c6 | 4268 | const struct bpf_func_proto *fn; |
79741b3b | 4269 | const int insn_cnt = prog->len; |
81ed18ab AS |
4270 | struct bpf_insn insn_buf[16]; |
4271 | struct bpf_prog *new_prog; | |
4272 | struct bpf_map *map_ptr; | |
4273 | int i, cnt, delta = 0; | |
e245c5c6 | 4274 | |
79741b3b AS |
4275 | for (i = 0; i < insn_cnt; i++, insn++) { |
4276 | if (insn->code != (BPF_JMP | BPF_CALL)) | |
4277 | continue; | |
e245c5c6 | 4278 | |
79741b3b AS |
4279 | if (insn->imm == BPF_FUNC_get_route_realm) |
4280 | prog->dst_needed = 1; | |
4281 | if (insn->imm == BPF_FUNC_get_prandom_u32) | |
4282 | bpf_user_rnd_init_once(); | |
79741b3b | 4283 | if (insn->imm == BPF_FUNC_tail_call) { |
7b9f6da1 DM |
4284 | /* If we tail call into other programs, we |
4285 | * cannot make any assumptions since they can | |
4286 | * be replaced dynamically during runtime in | |
4287 | * the program array. | |
4288 | */ | |
4289 | prog->cb_access = 1; | |
80a58d02 | 4290 | env->prog->aux->stack_depth = MAX_BPF_STACK; |
7b9f6da1 | 4291 | |
79741b3b AS |
4292 | /* mark bpf_tail_call as different opcode to avoid |
4293 | * conditional branch in the interpeter for every normal | |
4294 | * call and to prevent accidental JITing by JIT compiler | |
4295 | * that doesn't support bpf_tail_call yet | |
e245c5c6 | 4296 | */ |
79741b3b | 4297 | insn->imm = 0; |
71189fa9 | 4298 | insn->code = BPF_JMP | BPF_TAIL_CALL; |
79741b3b AS |
4299 | continue; |
4300 | } | |
e245c5c6 | 4301 | |
89c63074 DB |
4302 | /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup |
4303 | * handlers are currently limited to 64 bit only. | |
4304 | */ | |
4305 | if (ebpf_jit_enabled() && BITS_PER_LONG == 64 && | |
4306 | insn->imm == BPF_FUNC_map_lookup_elem) { | |
81ed18ab | 4307 | map_ptr = env->insn_aux_data[i + delta].map_ptr; |
fad73a1a MKL |
4308 | if (map_ptr == BPF_MAP_PTR_POISON || |
4309 | !map_ptr->ops->map_gen_lookup) | |
81ed18ab AS |
4310 | goto patch_call_imm; |
4311 | ||
4312 | cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf); | |
4313 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { | |
4314 | verbose("bpf verifier is misconfigured\n"); | |
4315 | return -EINVAL; | |
4316 | } | |
4317 | ||
4318 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, | |
4319 | cnt); | |
4320 | if (!new_prog) | |
4321 | return -ENOMEM; | |
4322 | ||
4323 | delta += cnt - 1; | |
4324 | ||
4325 | /* keep walking new program and skip insns we just inserted */ | |
4326 | env->prog = prog = new_prog; | |
4327 | insn = new_prog->insnsi + i + delta; | |
4328 | continue; | |
4329 | } | |
4330 | ||
109980b8 | 4331 | if (insn->imm == BPF_FUNC_redirect_map) { |
7c300131 DB |
4332 | /* Note, we cannot use prog directly as imm as subsequent |
4333 | * rewrites would still change the prog pointer. The only | |
4334 | * stable address we can use is aux, which also works with | |
4335 | * prog clones during blinding. | |
4336 | */ | |
4337 | u64 addr = (unsigned long)prog->aux; | |
109980b8 DB |
4338 | struct bpf_insn r4_ld[] = { |
4339 | BPF_LD_IMM64(BPF_REG_4, addr), | |
4340 | *insn, | |
4341 | }; | |
4342 | cnt = ARRAY_SIZE(r4_ld); | |
4343 | ||
4344 | new_prog = bpf_patch_insn_data(env, i + delta, r4_ld, cnt); | |
4345 | if (!new_prog) | |
4346 | return -ENOMEM; | |
4347 | ||
4348 | delta += cnt - 1; | |
4349 | env->prog = prog = new_prog; | |
4350 | insn = new_prog->insnsi + i + delta; | |
4351 | } | |
81ed18ab | 4352 | patch_call_imm: |
79741b3b AS |
4353 | fn = prog->aux->ops->get_func_proto(insn->imm); |
4354 | /* all functions that have prototype and verifier allowed | |
4355 | * programs to call them, must be real in-kernel functions | |
4356 | */ | |
4357 | if (!fn->func) { | |
4358 | verbose("kernel subsystem misconfigured func %s#%d\n", | |
4359 | func_id_name(insn->imm), insn->imm); | |
4360 | return -EFAULT; | |
e245c5c6 | 4361 | } |
79741b3b | 4362 | insn->imm = fn->func - __bpf_call_base; |
e245c5c6 | 4363 | } |
e245c5c6 | 4364 | |
79741b3b AS |
4365 | return 0; |
4366 | } | |
e245c5c6 | 4367 | |
58e2af8b | 4368 | static void free_states(struct bpf_verifier_env *env) |
f1bca824 | 4369 | { |
58e2af8b | 4370 | struct bpf_verifier_state_list *sl, *sln; |
f1bca824 AS |
4371 | int i; |
4372 | ||
4373 | if (!env->explored_states) | |
4374 | return; | |
4375 | ||
4376 | for (i = 0; i < env->prog->len; i++) { | |
4377 | sl = env->explored_states[i]; | |
4378 | ||
4379 | if (sl) | |
4380 | while (sl != STATE_LIST_MARK) { | |
4381 | sln = sl->next; | |
4382 | kfree(sl); | |
4383 | sl = sln; | |
4384 | } | |
4385 | } | |
4386 | ||
4387 | kfree(env->explored_states); | |
4388 | } | |
4389 | ||
9bac3d6d | 4390 | int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) |
51580e79 | 4391 | { |
cbd35700 | 4392 | char __user *log_ubuf = NULL; |
58e2af8b | 4393 | struct bpf_verifier_env *env; |
51580e79 AS |
4394 | int ret = -EINVAL; |
4395 | ||
58e2af8b | 4396 | /* 'struct bpf_verifier_env' can be global, but since it's not small, |
cbd35700 AS |
4397 | * allocate/free it every time bpf_check() is called |
4398 | */ | |
58e2af8b | 4399 | env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); |
cbd35700 AS |
4400 | if (!env) |
4401 | return -ENOMEM; | |
4402 | ||
3df126f3 JK |
4403 | env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * |
4404 | (*prog)->len); | |
4405 | ret = -ENOMEM; | |
4406 | if (!env->insn_aux_data) | |
4407 | goto err_free_env; | |
9bac3d6d | 4408 | env->prog = *prog; |
0246e64d | 4409 | |
cbd35700 AS |
4410 | /* grab the mutex to protect few globals used by verifier */ |
4411 | mutex_lock(&bpf_verifier_lock); | |
4412 | ||
4413 | if (attr->log_level || attr->log_buf || attr->log_size) { | |
4414 | /* user requested verbose verifier output | |
4415 | * and supplied buffer to store the verification trace | |
4416 | */ | |
4417 | log_level = attr->log_level; | |
4418 | log_ubuf = (char __user *) (unsigned long) attr->log_buf; | |
4419 | log_size = attr->log_size; | |
4420 | log_len = 0; | |
4421 | ||
4422 | ret = -EINVAL; | |
4423 | /* log_* values have to be sane */ | |
4424 | if (log_size < 128 || log_size > UINT_MAX >> 8 || | |
4425 | log_level == 0 || log_ubuf == NULL) | |
3df126f3 | 4426 | goto err_unlock; |
cbd35700 AS |
4427 | |
4428 | ret = -ENOMEM; | |
4429 | log_buf = vmalloc(log_size); | |
4430 | if (!log_buf) | |
3df126f3 | 4431 | goto err_unlock; |
cbd35700 AS |
4432 | } else { |
4433 | log_level = 0; | |
4434 | } | |
1ad2f583 DB |
4435 | |
4436 | env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT); | |
4437 | if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) | |
e07b98d9 | 4438 | env->strict_alignment = true; |
cbd35700 | 4439 | |
0246e64d AS |
4440 | ret = replace_map_fd_with_map_ptr(env); |
4441 | if (ret < 0) | |
4442 | goto skip_full_check; | |
4443 | ||
9bac3d6d | 4444 | env->explored_states = kcalloc(env->prog->len, |
58e2af8b | 4445 | sizeof(struct bpf_verifier_state_list *), |
f1bca824 AS |
4446 | GFP_USER); |
4447 | ret = -ENOMEM; | |
4448 | if (!env->explored_states) | |
4449 | goto skip_full_check; | |
4450 | ||
475fb78f AS |
4451 | ret = check_cfg(env); |
4452 | if (ret < 0) | |
4453 | goto skip_full_check; | |
4454 | ||
1be7f75d AS |
4455 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); |
4456 | ||
17a52670 | 4457 | ret = do_check(env); |
cbd35700 | 4458 | |
0246e64d | 4459 | skip_full_check: |
17a52670 | 4460 | while (pop_stack(env, NULL) >= 0); |
f1bca824 | 4461 | free_states(env); |
0246e64d | 4462 | |
9bac3d6d AS |
4463 | if (ret == 0) |
4464 | /* program is valid, convert *(u32*)(ctx + off) accesses */ | |
4465 | ret = convert_ctx_accesses(env); | |
4466 | ||
e245c5c6 | 4467 | if (ret == 0) |
79741b3b | 4468 | ret = fixup_bpf_calls(env); |
e245c5c6 | 4469 | |
cbd35700 AS |
4470 | if (log_level && log_len >= log_size - 1) { |
4471 | BUG_ON(log_len >= log_size); | |
4472 | /* verifier log exceeded user supplied buffer */ | |
4473 | ret = -ENOSPC; | |
4474 | /* fall through to return what was recorded */ | |
4475 | } | |
4476 | ||
4477 | /* copy verifier log back to user space including trailing zero */ | |
4478 | if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) { | |
4479 | ret = -EFAULT; | |
4480 | goto free_log_buf; | |
4481 | } | |
4482 | ||
0246e64d AS |
4483 | if (ret == 0 && env->used_map_cnt) { |
4484 | /* if program passed verifier, update used_maps in bpf_prog_info */ | |
9bac3d6d AS |
4485 | env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, |
4486 | sizeof(env->used_maps[0]), | |
4487 | GFP_KERNEL); | |
0246e64d | 4488 | |
9bac3d6d | 4489 | if (!env->prog->aux->used_maps) { |
0246e64d AS |
4490 | ret = -ENOMEM; |
4491 | goto free_log_buf; | |
4492 | } | |
4493 | ||
9bac3d6d | 4494 | memcpy(env->prog->aux->used_maps, env->used_maps, |
0246e64d | 4495 | sizeof(env->used_maps[0]) * env->used_map_cnt); |
9bac3d6d | 4496 | env->prog->aux->used_map_cnt = env->used_map_cnt; |
0246e64d AS |
4497 | |
4498 | /* program is valid. Convert pseudo bpf_ld_imm64 into generic | |
4499 | * bpf_ld_imm64 instructions | |
4500 | */ | |
4501 | convert_pseudo_ld_imm64(env); | |
4502 | } | |
cbd35700 AS |
4503 | |
4504 | free_log_buf: | |
4505 | if (log_level) | |
4506 | vfree(log_buf); | |
9bac3d6d | 4507 | if (!env->prog->aux->used_maps) |
0246e64d AS |
4508 | /* if we didn't copy map pointers into bpf_prog_info, release |
4509 | * them now. Otherwise free_bpf_prog_info() will release them. | |
4510 | */ | |
4511 | release_maps(env); | |
9bac3d6d | 4512 | *prog = env->prog; |
3df126f3 | 4513 | err_unlock: |
cbd35700 | 4514 | mutex_unlock(&bpf_verifier_lock); |
3df126f3 JK |
4515 | vfree(env->insn_aux_data); |
4516 | err_free_env: | |
4517 | kfree(env); | |
51580e79 AS |
4518 | return ret; |
4519 | } | |
13a27dfc JK |
4520 | |
4521 | int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, | |
4522 | void *priv) | |
4523 | { | |
4524 | struct bpf_verifier_env *env; | |
4525 | int ret; | |
4526 | ||
4527 | env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); | |
4528 | if (!env) | |
4529 | return -ENOMEM; | |
4530 | ||
4531 | env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * | |
4532 | prog->len); | |
4533 | ret = -ENOMEM; | |
4534 | if (!env->insn_aux_data) | |
4535 | goto err_free_env; | |
4536 | env->prog = prog; | |
4537 | env->analyzer_ops = ops; | |
4538 | env->analyzer_priv = priv; | |
4539 | ||
4540 | /* grab the mutex to protect few globals used by verifier */ | |
4541 | mutex_lock(&bpf_verifier_lock); | |
4542 | ||
4543 | log_level = 0; | |
1ad2f583 | 4544 | |
e07b98d9 | 4545 | env->strict_alignment = false; |
1ad2f583 DB |
4546 | if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) |
4547 | env->strict_alignment = true; | |
13a27dfc JK |
4548 | |
4549 | env->explored_states = kcalloc(env->prog->len, | |
4550 | sizeof(struct bpf_verifier_state_list *), | |
4551 | GFP_KERNEL); | |
4552 | ret = -ENOMEM; | |
4553 | if (!env->explored_states) | |
4554 | goto skip_full_check; | |
4555 | ||
4556 | ret = check_cfg(env); | |
4557 | if (ret < 0) | |
4558 | goto skip_full_check; | |
4559 | ||
4560 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); | |
4561 | ||
4562 | ret = do_check(env); | |
4563 | ||
4564 | skip_full_check: | |
4565 | while (pop_stack(env, NULL) >= 0); | |
4566 | free_states(env); | |
4567 | ||
4568 | mutex_unlock(&bpf_verifier_lock); | |
4569 | vfree(env->insn_aux_data); | |
4570 | err_free_env: | |
4571 | kfree(env); | |
4572 | return ret; | |
4573 | } | |
4574 | EXPORT_SYMBOL_GPL(bpf_analyzer); |